are there stupid advice in there? No doubt she isn’t taking her own advice she is dishing out to others

A lot of families co sleep. I am personally uncomfortable with it but I know many people who are not. BM still has ss12 sleep on a couch in her room while her hubby and son sleep with her in the bed. Not my cup of tea but we can’t control them and you can’t let BM control your home environment. We limit contact with the other house to one phone call a week and that is reciprocated. However in our case, ss feels sad whenever he talks to the other parent and would rather just leave it alone. To each their own.

I have an odd feeling they'll be slightly messed up and we'll have to clean it up in the future

I'm not trying to be mean just honest but I doubt you'll have to worry about fixing them. Sadly I'd bet money that they'll go no contact as preteens if this continues. I think cosleeping goes along with the enmeshment that is common with PAS.

SD still sleeps with mom at 17 years old. She never mentioned she had any issues with not sleeping with us and I met her a week after she turned 6. BM told us a few years ago when SD went no contact that part of it was because she didn't feel comfortable staying with because us she wasn't allowed in our bedroom. I'm sure that this was one of the many ways BM convinced SD that her daddy didn't care.

The BM2 I deal with is certified psycho YET she is a highly qualified psych nurse with a Masters degree.  The irony...

Many years ago i used to wake up to find my three year old son had crept in and placed himself at the foot of the bed. I would return him to his own bed whilst he slept. There’s nothing wrong with co sleeping when they are little. But they do need to learn not to be clingy. Personally I wouldn’t co sleep with a girl older than six - by the time they are eight or nine they can start developing features... and I would find it a bit disturbing if my daughter was co sleeping in a bed at that age with two parents in it. I found a good way round co sleeping (at the time I was a single parent). When they were about primary school age I would pop cartoons on in my bedroom for thirty mins and they would be at the end of the bed and chuckle away together. Then quick story and bed. I wouldn’t say it’s better than co sleeping, just an alternative. It doesn’t have to be tv either it could be reading or the radio something. 

I will say that my nieces, who didn't co-sleep, had a hard time sleeping on a different floor from their parents when they were young.  Your SD might really have developed some anxiety about that, it can happen even if she's been sleeping on another floor for a year.

If there is a way for her to sleep on the same floor without co-sleeping, you might want to do it.  My sister and her husband moved guest room upstairs so the kids could move downstairs.

I am pro cosleeping, but NOT WITH OTHER PEOPLE’S CHILDREN. 

BM used skid as an emotional tool, in the beginning, because she still coslept with skid at home (unless BM had a “friend” over for the night), and wanted DH to do the same. I’ll NEVER forget the time BM called DH enraged that we wouldn’t allow skid in our bed, and put an emotionally hysterical young skid on the phone to tell daddy that she wanted to sleep with him. 

Even between siblings.

I used to cosleep with my mom but always wanted to sleep on my own. Always felt like it ws more for her than for me.

My two ss used to cosleep. Ss12 asks to cosleep with ss7 every once in awhile. It is very weird. The little one likes having his own bed but still sleeps with a stuffed animal.  Both the moms coslept. BM2 still babytalks to ss12.

Ss12 was given his own room bc puberty hit. He is happily sleeping in his room.