Avios.com HHA is a single pot with mutliple names against it, unlike a BAEC HHA where it is a wrapper for individual pots.

As such, an Avios.com HHA will be considered based upon the last transaction regardless of who made it.
If form an Avios.com HHA, I guess it would similalry be considered based upon the last activity of any of the members prior to formation.

Avios points from Avios.com HHA can NOT be transfered into BAEC accounts or IB+ accounts at all.

Disolved: Don't take the p|ss, or it will spoil things for everyone.

How many do they have? Personally, if it is a decent number, I'd probably get them some activity regardless of setting up the HHA, just in case there is a delay.