When DH and I married, his dad refused to send the response card back. DH called him and asked if he and his second wife, and 8 step brothers would be attending the wedding. He still said "I don't know, we'll see." Mind you, the wedding was in the same town in which they live, about 10 miles from their home.
The poor caterer set up a table (after all, he was the father of the groom), and when they didnt show up, had to make the table disappear without calling attention to the fact that DH's dad wasnt there.
Fast forward 25 yrs, and now DD is planning her DFW. We called DH's dad and told him the plan - WP, LS, sit down dinner. He says - oh, we might be spending that month in FL, so maybe we'll drop by. Seriously! Not as a joke! Now this is probably rude, but Im not going to go thru this all over again. I sent him a nice note and said that we need to have an answer, b/c Disney is magical but they have their rules. He still hasnt given us a yes or no. I am going to assume he's not coming this time. Moral of the story - some people will just not commit themselves.