The different response illustrate 2 issues. One that we do not know the nuances of your relationship or how this trip came to be arranged. The other, that we are all different in how we look at it and what we can simply afford to do. We've done MANY family trips over the past 13 years to
DVC and other timeshares, we cover the accommodations and invite people, I am appreciative if they ask to pay but would be upset with them if they truly insisted. But I also don't involve them in the planning process unless I have a simple preference question to ask anyone. I plan the trip, decide who to invite, etc. I generally require we go out to dinner as a group, that's it. We've had as many as four 2 BR units ocean front on HH, nine 1 & 2 BR DVC units, nine 2 & 3 BR units in Gatlinburg and upcoming, seven 2 BR units in Nashville.
From a financia point of view, the difference in points between what you would have spend and what you did multiplied by a fair rental factor of $8-10 a point is about as neutral as you'll get for points that were not distressed otherwise.
One word of caution is that many have the impression that timeshares are free once you buy them. Therefore, what you and I would consider a cheap price, someone else might think you were trying to rip them off and react accordingly. Tread lightly for any charges.