I'm not keen on any of them, but I like Callaghan best out of these.
Lafferty reminds me too much of Rafferty, and I'd be inclined to accidentally say Rafferty instead of Lafferty. Lafferty doesn't really have a nice nickname possibility either.
Callaghan sounds nice, and my only objection to this as a FN is that it's a surname (but I'm assuming that's exactly the point for you in considering to use it).
I don't really like the sound of Wason, but that's not new news :)
All in all, considering that they're meaningful names to you, I'd think they'd be perfect in the MN slot. Also, there are nicer names to use as FNs in your family tree.
However, since you asked for MNs for them:
Some ideas to keep them all family (/family related) names:
Wason
RussellWason
KennedyWason
PatrickCallaghan
AulayCallaghan
RussellCallaghan
BaxterCallaghan
PatrickLafferty
ShannonLafferty Wason
Lafferty
Rodger
Other suggestions:
Wason
GabrielWason
MatthiasWason
LeanderWason
BlaiseWason
AlexanderWason
ConradCallaghan
DavidCallaghan
JackCallaghan
RemyCallaghan
MagnusCallaghan
ShayCallaghan
DashiellLafferty
JamesLafferty
RemielLafferty
SimeonLafferty
GideonLafferty
JulesLafferty
Gage