Respectfully disagreeing with the idea of laughing about the glasses (unless you do it just inside your head, celeb). They might take that as some kind of unwelcome criticism. You offered to buy them more traditional glasses, once before and they declined. Nothing more you can do about that, IMO. Obviously, they think they're ok, probably even like them, so I guess you and DH will just have to accept that. Not the biggest problem in the world, as I know you know.
The idea of keeping visits to the summer time is a good one, IMO, celeb. That way, at least, you don't have to worry about being cold. Would it be possible, also, to stop and get something to eat on your way to their home? Cuz if DS isn't there or hasn't prepared anything, you now know you may have a long wait till you get to eat anything. You shouldn't have to do this, I know, but it may make things more comfortable for you.
Sorry to hear that DS has to help support his partner's DSs. But she's not divorced yet - maybe in the court proceedings some child support will be worked out? Not your call, I understand, just wondering if you know if that's in the works. Regardless, as you say, if DS is happy w/ this situation, then it's ok.
@ All - I'm going to chime in w/ the good wishes for those who were alone and Xmas. And sending best wishes to all for a Happy New Year!