"Where does it say son has reconnected?? I can’t see this? "
SB74, he messaged her a compliment on the GC's present. I think that's what NotSpaghetti meant by "reconnected."
Grandmablue, my heart goes out to you! First, I am deeply sorry about DH's (dear husband's) face cancer and loss of an eye. What a heartbreaking experience! I hope he's doing ok now. Also, I'm sorry that you have been poorly, as well. And, of course, I'm sorry that ODS (older dear son) is keeping his kids away from you.
I imagine DH's experience w/ cancer makes him even less patient w/ backtalk, etc. While I agree that you and he need to accept the way that ODS and ODIL raise their kids, if he feels disrespected by OGD (oldest granddaughter), IMO, he has a right to speak up. IDk what he argues w/ her about, overall. If he's trying to tell her she can't do things her parents allow, then he's out of line. But, IMO, he has a right to say "Don't talk back to me," even if the parents permit backtalk. He has a right to establish how he is to be treated. And he certainly has a right to object - and so do you - if she kicks you!
Other than that, I agree with PPs (previous posters) that it is up to the parents how they raise their kids. I take it you and DH don't like that fact that they are raising their children "via a book," one that promotes some different childrearing methods than you two are used to. IMO, you have a right to your opinion about this, but you need to keep it to yourself and not give any indication that you disapprove (if that has been a problem). Strict schedules, for example, may work best for their family, even if you and DH don't agree or if, unfortunately, their schedules don't coincide w/ yours. ODS' siblings have no business trying to assert their childrearing beliefs w/ him and ODIL either, and I'm glad you've asked them to avoid falling out w/ them.
No doubt, your story is confusing, but I take it that another problem is that ODS feels you prioritize other things over his kids? IMO, he is being unrealistic and oversensitive. He has no right to expect you to travel to see gymnastics class every week or at all. It's nice, though, that he wants you to be involved in their lives (some GPs would give their eye teeth for this!), and "sometimes" may seem too vague to him. I know you didn't ask for advice, but can't help but wonder... Could you compromise and go, say, once a month or once every other month? At least, then he would know you're committed to being there for them.
If, for whatever reason, he suspects you're not truly interested in his kids, he may have misinterpreted the missed 5:30 contact as proof of that. Did you explain to him that a meeting ran over time? What was his response to that?
As for the gifts, I don't see any harm in your sending them, unless you've been asked not to. Rock and hard place. The fact that you weren't invited to the party could have been a signal not to send gifts either, but not doing so could also have been interpreted, once again as "not interested" and "bad granny." I'm glad you sent them and that you got a positive reaction.
I don't think it's "rude" either to send a gift for the birthday child's sibling, as well. In my family, we always do that though it's usually a smaller, less expensive gift than for the bday child. We do it so the other child doesn't feel left out. the bday child is generally too excited w/ their own gifts to mind their sibling getting one small thing. Nothing wrong w/ it, IMO, and actually very generous of you.
Then again, I don't think it was rude for ODS to ignore the group message or remove himself from the conversation. I often see people do that in group chats if they're on the outs w/ some of the people in the group or aren't interested in what's being discussed. If ODS wasn't speaking to you at the time (you didn't say), then it doesn't surprise me that he left the conversation. In fact, I would have expected it.
I may be wrong, but I think his text about the gifts is partly his way of showing you that he responds when he feels you have given thought to his kids. I hope this opens up the lines of communication, but I know you're "not sure" if you "want to med bridges," so IDK how that will work out. If you do want to try again, I would let ODS know that if you miss one of those FTs, it's b/c of work, not b/c you've "forgotten" about them and to let you know if you can call later in those circumstances.
"I’ve put so much into my grandson because I know my daughter would never stop me seeing him."
Has ODS complained about the time/effort you give to GS? Does he think you're favoring him? I understand "self-preservation," but please make sure you treat all your grands as equally as the parents will allow. ODS needs to understand, though, that if he keeps his kids away from you or is rigid about when you can see them or not, that you are likely to become more involved w/ GS. That's just reality.
As PPs have said, however, I don't think it's a good idea to invest too much of yourself (general you) in any one C or GC. Fortunately, you also have DH and your work. I hope you also enjoy time w/ friends, DH, and maybe even just by yourself, reading a good book, maybe, or watching favorite television shows.
Whether you resume communication w/ ODS or not, I wish you and DH the best. Hugs!