BM forbids it
H's kids live with mom in another state 300+ miles away. We get them about 4 times a year in addition to spring break and summer, and sometimes Christmas. I've been married to H for over a decade. I have a decent rapport with SD20 who won't be coming this summer because she has a job (so far; she got off for spring break so we'll see). H and his X split when SS14 was 1 and he is BM's golden child, so it's different with him. BM, a while back, insisted that I was not to co-parent because I am not their parent. I have somewhat disengaged, but I do not want anything negative she says about me to be true in their eyes. It is ultimately up to the kids what their perspective is, but I'll not disengage to the point they think I do not care or don't like them. I may dislike some of their behaviors or attitudes, (mainly the ones adopted from BM's influence) but I like them.
BM calls H and basically tells him that his time with SS was to be with just him. Texts during spring break consisted of BM interrogating SS about my whereabouts and pushing him to not like my presence. H takes the phone at night so SS will sleep, otherwise, he won't. Do I use the time when SS is here to interact more and teach him some life skills when the moment calls for it or keep my distance?