Hi.
I think alanon would be a great thing to do for yourself. You can't control or manage any of your siblings but you can find ways to keep your own peace and serenity.
The Serenity Prayer is.
God grant me the serenity
to accept the things I cannot change;
courage to change the things I can;
and wisdom to know the difference.
You can't change your brother, or your sisters response to your brother.
What can you do to have a pleasant Christmas? I wouldn't put my chickens in the 'poor, alcoholic, bachelor that has not made any contact on the subject with only 25 days to go' basket. You can't make him make plans but you can make your own.
