Solder on the legs on to the MultiFET pcb, not through.
Too much heat, That's why the pad has lifted.Oli, I realise this is late in the day, but I've only just fitted my MultiFETs.
I'm only posting this to hopefully save anyone else the same problem
It may be that I have a pair of not very well made boards, but soldering directly to the pads resulted in a pad lifting.
And that was just by gently flexing a wire when fitting to the main board..
I found it a lot better to use the correct size wire, and fit through the hole, which gave some structural strength.
As I'm building an exposed valve version, and have populated the bottom side, I mounted the board through the three holes, then bent the legs 90 degrees and soldered to the SMD pads on the top side.
Certainly, at least on the MultiFET boards I have, the pads are really delicate.