Embarc allows "rentals" for points, (or simply the rental of any Embarc booking, by adding a guest name) between members. It's not direct and does involve a 3 point phone call.
It requires an existing booking to which the "rented" points can be transfered and once done, the points of the person with the original booking return to their account to be used again.
We have a very active, private FB group (must be an Embarc member) which allows members to do this. It allow members to get extra points (at cost) for travel for a specific year(s) without have to buy more membership points permanently. The person offering the points can get their fees paid directly by the renter or through a fund transfer between the 2 involved.
Cost is $35usd per transaction.
Adding a guest to an existing booking is free and can be done online.