Who signs v5 when not there on collection day?

[Purpleparrotuk]

Hi. I have started the process of voluntary termination today. I now have to wait for BCA to call me with a collection date. I am leaving the car at the dealers when I pick my old one up and BCA will collect from there, which could be a number of weeks yet. I have been told I need to leave the V5 with the car and just fill out section 9 and send it off when collected. Does the collector from BCA sign this section as well before I send it off? It's actually the finance companies name address that will be entered in here. Do I just make sure the dealer gets BCA to sign that section and then give it back to me? Thanks.