DH has 'big' birthday on Monday & weeks ago I decided to invite his siblings & families for surprise party at ours (we've just built a home bar & would be perfect!) he knew 1 sibling & family were coming for the weekend as they need to stay but finally put 2&2 together & said "hope this isn't some sort of surprise party - you know I'd hate that, if you have I'll just walk out" etc etc. Obviously I did tinkly laugh & assured him of course not, just co-incidence!! But, am now shitting bricks at prospect of said party  so far I've dropped in that 1 more may drop over on Sat because, um, sister, but no mention she's bringing 5 with her and 2 other siblings plus family are coming too...! Should I say something now (and risk huge row of 'I told u I didn't want etc etc) or just let them arrive and act surprised they are all here and, "oh gosh, isn't it amazing I've done far too much food" so they are all catered for?!