I really would appreciate some solid advice here, as I am somewhat at a loss on how to handle this situation. 

I'm new here but thought I'd start sharing. 

A little back ground - I am BM to 3 BS's - all grown,working, and successfully raising their own families - they are delights to be around. I am SM to 3 SS's - 2 from Wifey#1 who raised (pretty much on her own) 2 delightful, hardworking yound men who are also working and raising their own families, and 1 from BM (wifey#2) who is a trainwreck and her evil spawn didn't fall far from the crack house. 

I didn't write Part 2 yesterday because I decided to leave the chaos surrounding SD16 lie for a minute and try to have a great day.  I scooped up puppy and took him on work errands away from home.  I'm glad I did!  

Does anyone else out there feel like somewhere along your stepparent journey your life got swept up in a monsoon of other people's dysfunction?  I was single for over 10 years and fiercely dedicated to raising my DS and living my best, most emotionally healthy, peaceful, and happy life.  Then I fell in love with BF/SO and we have been living together and sharing our life for 6 years now.  SO has 5 kids...SD22, SD20, SD16, SS15, and SS10...3 BMs.  Yeah, I should've known better, right?  I actually started this out with such hope and was positive that we would all bring great things to each o

My fiancé and I have been together three years now, we met at work and started as a fling, I was 21 when we first met. Then as time went on he saw I was pretty decent with his daughter, I honestly blame that on the fact I have 14 nieces I had to help raise, so yeah I’m okay with kids but after so long I lost traction. When we became serious I just sort of froze up and became my mother with better skin tone. I find myself always mad.

Okay so here goes( a bit lengthy)

DH seems oblivious to SS12 manipulations. When I bring it up he makes excuses for SS12 and tells me he is a good kid.

The past few weekends and days he has been "forgetting" his bookbag(with homework) at BM house. DH gives lecture about how important homework is then does nothing but spends hundreds of dollars on the kid and lets him play videogames.

His grades are slipping. DH gives lecture but refers kid to me for privileges such as videogames.

I’ve brought this up before but I’m not sure if there’s a better way to handle this.

SO’s little one is 5. He and his sister have been completing every other weekend visitation in our home for over a year now. There have been no problems or major changes in our home or living situation since my partner moved in.