not sure if i am posting this in the right place, i already posted it in am i being unreasonable...but here goes.
ok bit of background here.
my dad was married previously when he was 16yrs old. He and his wife split and after 5 years he lost contact with his 2 children from that marriage. to cut a long story short my "brother" contacted me before xmas asking if we could meet to which i said yes.
He stayed with me for 5 hours and at the end of it said he could never see us sitting down as a family....fine by me iyswim?
However via me he made contact with my sister and mum, he has continued contact with my sister but not mum or I. I sent him an email over a week ago asking how he his children and wife were and whether they had any plans for his daughters birthday. I have not recieved a reply. My problems begin here.
My nephews birthday is the day after my nieces birthday, now i know that arrangements have been made for us "all" to go to the coast for the day. I feel like it is going to be very uncomfortable for me as he cannot even be bothered to reply to my emails even though he emails my sister almost daily, I also feel she is partly to blame as when I had ds2 baptised I did not invite him as my brother who i grew up with was more important for being there, if that makes sense. But she went and told him nonetheless.
I do not want to let my nephew down as he is my baby ( my sister had 5 miscarriages before she had him and he is so special to me) BUT i don't want to be in an uncomfortable situation with my 2 children iyswim?
With that many young children there, the focus and attention will much more be on crowd control and them having fun than the interactions between the adults, imo. I've been in some really awkward family situations where I've been worried ahead of time about my DC picking up on the bad feeling between some of the adults, and they never have.
If I were you, I'd try to go along with as open a mind as possible. Your half-brother is likely to have quite a lot of emotional turmoil and angst after losing contact with your dad. Perhaps he has happened to just click with your sister, and means no harm to you, but isn't mature enough to realise that he could be upsetting you? Perhaps he purposely wants to drive a bit of a wedge, to get his own back at some level for losing touch with his father? Or perhaps he is easily hurt himself, and offended over the christening thing? There are loads of scenarios that could be the case, but it seems very clear that you want to protect you and your sisters relationship, and I think the best way to do that is go along, look like you're having fun, and be polite to everyone.
Agree with hedgie. Go along, put on your best smile and have fun. Ignore any bad feeling and rise above it. If he is playing the old 'divide and conquer' card, then let him play it, it is silly and immature. The newness of this relationship he has with your sister will wear off at some point and hopefully allow you all to get back onto a more even footing.