If you cancel at least 31 days in advance, the points are returned to your account with the same status they had just prior to making the reservations. The only problem that might arise would be if you are beyond your banking deadlines. That depends on your use year. If you can't bank, then yes ,you would have to use the points by year end or lose them.
I assumed you would know at least 31 days in advance if your friends would be joining you. I also assumed that you were "saving" current use year points for them to use. If so, it didn't seem to matter if those points were holding a reservation or just sitting in your account while your friends waited for the tax refund.
If you have to borrow points for your friend's reservation, then I see why you are reluctant to do so until they commit.
Were you perhaps planning to bank your points for this year and then borrow next year's points to make your friend's reservation if they decide to go? If so, I understand why you don't want to reserve now.
Friends often just don't understand how things work. Aside from the possibility of losing your points assume you told them that the longer they wait, the less likely it is that there will be studios left at the BCV.
Hope it all works out for you -