If your DH doesn't think it's a big deal, you need to let it go.

You DH simply needs to tell her no. It's his time and he's not obligated to let her do this. Any time he loses over this is because he let's her get away with it.

Yup, I deal with that all the time. It happens even more now that DH and I are married and own our own home. It used to be that BM was always expecting DH to drop everything and take the kids for her weekends because something came up for her. Now, she's moved it to try to take DH's weekends away from him.

Just this year alone, she booked plane tickets for the children to come home their spring break with their grandparents on Saturday evening of DH's weekend. They didn't leave until the Monday before, so were home for all of BM's weekend, but god forbid she should actually book tickets that get them home in time for DH's visit. Last year, she booked the tickets so they left in the middle of Sunday on DH's weekend and then insisted he be in charge of taking them to the airport. During their last mediation, she took spring break away from DH to allow the kids to go to their grandparents' winter home every year (their grandparents' live 2 miles from her during the spring, summer, and fall, so it's not as if the kids never see them). This was fine for us, because then DH won't have to take an extra week off of work to entertain the kids (he doesn't get paid time off and we're not in a position to take a fancy vacation with them). After taking his week away from him, BM then had the nerve to complain that now she had to "sacrifice" by taking time off for the kids during winter break and she expected him to switch.

Then just a few weeks ago, she sent DH and angry text saying she needed him to switch weekends because she booked her vacation (an RV trip, so no plane tickets or hotel reservations involved) over DH's weekend. She even said to him "I'll bring home the kids early to avoid a fight with you if you don't agree" before he'd even had a chance to respond. So, nothing like not only taking his time, but then also acting like he's going to be a jerk about it (instead of apologizing for her oversight). Again, they did not start their vacation on BM's weekend because her boyfriend had a poker tournament, so they had to stick around, but by all means take DH's time.

With one SS, who BM has grown particularly close to in the last year, there have been a litany of excuses of sporting events, birthday parties, etc that he has on DH's weekend. He's called a couple of times to say "dad, to make it easier on you, I'll just stay home, so you don't have to drive me to my events." What 10 year old is concerned about "making it easier" on a parent? Also, BM didn't care that DH was driving to and from events in the years before DH and I were married.

All this is from a BM who complains incessantly about how difficult her life is because she has the kids most of the time (she leaves out the fact that DH has tried to discuss more custody time, even proposing 50/50, but she flat out refused). In my case, BM is also out for money, so even if she wanted less time with her kids, she would never give up the time because that would mean less money for her.

There's some weird power struggles going on with her for sure.

It's maybe bad of me, but I don't really mind when the one SS doesn't come for the weekend, because he's dramatic and difficult, so it's sometimes more pleasant when he's not with us. He's now taken to talking to BM on the phone twice a day while he is with us and texting her several times a day, so she's a constant presence when he is here. She doesn't talk to the other one at all when he is with us and he doesn't get all nervous when he doesn't hear from his mom or accuse DH of hating his mom, so it's much calmer when it's just him.

My skids are grown now but I/we did deal with it.

Like "StrugglingSM", while I was dating my dh, my skids bm would expect dh to drop what ever he was doing to have the kids. I personally think she was just trying to interfere with our plans. Then after we married bm had excuses to prevent the skids from visiting. She once said she was punishing ss for not cleaning his room and therefore he could not come over. 2 years in a row she took vacation during fathers day and had the kids out of state with her.

OP, is it possible that your skids bm is working on turning the kids against their father? That is what is sounds like to me. Sounds like bm is encroaching on dh time with kids and certainly not allowing any extra time.

many many MANY non custodial deal with Custodials making visitation very difficult if not impossible.

BM did this constantly (or tried to) with YSS, never OSS. There was a movie coming out the night he was scheduled to go back to DH's, and she "promised him" they'd see it together. Or she "had" to take him out for ice cream or to dinner, always on his time. Why on his time? Because that way, OSS would be out of the way and it could be her, her DH, and their biokid together. She wasn't fooling anyone. DH always said no. BM could take him out on dates on her time.

Your DH should realize this is a CLASSIC move right out of the PASinator GUBM playbook.
If he tries to go along to get along, he WILL regret it, mark my word.
Just another ploy to keep biodad from bonding with his children. It's ALWAYS some "innocent" sounding activity under the guise of being "for the children" (TM). Scouts, tball, swimming, staying with the GBM, etc etc. Makes dad look like an ogre if he doesn't agree to it but it will ALWAYS be on DAD'S time, you can bet your boots.

This is a very clever ruse in that it makes BM look like she is a caaaaaaarrrrrring parent, all the while graaaaadddduaally and slooooowwwwly taking visitation away from dad. Plus additional time with BM family members adds up to more opportunity to trash talk dad and SM in front of skids--more PAS brainwashing.

AND if dad is busy taxi-ing skids to events on his time and skids are at activities during his time, even LESS quality/bonding time with dad. A win, win, win scenario for the BM intent on cutting dad out from the child(dren)'s lives.

Your DH should wake up and smell the scheming. This happened to Chef and he "co-operated" to a T. As a result, all 3 skids were completely alienated in a matter of 4 years. Chef hasn't seen hide nor hair of them for 9 years (8 for YSS, now 14.5).

http://www.piffe.com/stories/camel-nose.php

My DH has been the victim of this. The sicker thing about this is that BM only does this to SD and not SS. BM did this with a sporting activity for SD16. It is twisted how she used this sport, events, various teams all throughout our state to alienate my DH. Signing up SD for tournaments that were 3 hours away every time we had her. Telling SD that I should stay home with SS and signing him up for various activities so I couldn't travel with my DH. By the way, it wouldn't work.... but at then end of the day, it came down to my husband refusing to have SD participate in an out-of-town team that would require 4 hours of travel 5 times a week back and forth. BM went so far as to set up a try-out on our day and having SD tell us she "just wanted to see if she could make it.". Finally (and looking back, against our better judgment) he relented and she stayed with BM who ran her back and forth. Nevermind my husband is an executive, excellent provider to both kids both financially and with time, etc. She is verbally abusive to me when she is there, a horrible hard-headed brat when she is with us. SS14 is amazing but BM has worked a number on SD. I am not sure it can ever be undone. It is so sad because psycho BM has systematically ruined SD's relationship with her dad.

"psycho BM has systematically ruined SD's relationship with her dad."
That was the original plan all along.