Any chance of any familiy members being able to move, still each in their own property but in adjacent properties ?
That could be very valuable for sharing rescources and defensive arrangements.

In the present economic climate, you might be able to buy several adjacent foreclosed properties cheaply.

It does presume of course that one or two of you have neighbours willing to sell.
Remember that gardens that back onto each other from houses in different roads, are arguably as useful as being next door neighbours.

Or could everyone sell up, and pool rescources to buy a single very large property with ample room for all.

Plenty of ground is desireable, both for crop growing and for building another home for relatives, or parking mobile homes or RVs (this is probably prohibited normally, but who cares after TSHTF)

If considering PV, make very certain that you are getting a stand alone battery charging system and not a grid tied one.
A grid tied PV system can be worthwhile economicly whilst BAU continues, but gives NO PROTECTION WHATSOEVER against power cuts.

Firearms are undoubetedly useful, but do not have too much faith in going armed, rememember that the other lot may be better armed, more numerous, or simply lucky.