Unless it hits them in the pocketbook!!!
We went to WDW with myself, DH (now, EH ), DS7, DD10, DM, DD, DB, DB, DSIL, DN1 about 18 years ago. All stayed in Poly. This was before PSs, so that was easier.
I made the ressies, but since we all had to have money IMMEDIATLEY to cover the first night, it was an easier situation. And it was a great time...We are all very much alike and still vacation together, from time to time, at WDW.
BUT...When the financial burden seems to all be falling on YOU.....LOOKOUT!!
I vote for letting them rent their own points and making their own plans.