We're just back from a tour of ILs. We spent the first night at BILs and it's always hard work. I can't face them without a drink!
They are very frugal and abstemious, they are quite disapproving of other family members alcohol intake and can be quite Calvinist.
I sensibly stopped a a nearby shop and arrived with a bunch of flowers and a bottle of chilled Sauvignon Blanc.
SIL accepted the wine with thanks but I never saw it again -It was a long evening!
Shall I have a hp flask in my handbag next time, call into the pub on the way or refuse to go again! 
Should add before the puritans chase me with pitchforksthat there are no religious sensitivities involved and I am not being entirely serious. 