Really really really dumb question (probably), but if my sim maxes skateboarding, he gets 100 * 1.01.
Then he goes to a house, (and after becoming good friends with the father Iam Tricky) and there are now 6 in the bed and the little one said roll over in the household and they all max bmx riding is that 700 (1 skateboard skill + 6 bmx skillls = 7 skills) x multiplier or 200 (1 skateboard skill + 1 bmx skill = 2 skills) x multiplier. In either case, the multiplier becomes 1.07.
My mind has just suddenly like gone all Homer Simpson like on me for some reason and I am (probably) confusing myself as a result.