Pick Across Families by Family IVs ? (Maybe feature request)

This may be a dumb request / question but I am throwing it out there anyway.

Its possible that it is possible I just haven't found a way to do it like this.

Potentially it could be hugely powerful if there was some way to implement it.

Hypothetical scenario

I have lots of sprites including multiple instances of an Enemy Character sprite (eg "EnemySprite").

This "EnemySprite" belongs to two families (eg EnemiesFamily & MovingObjectsFamily)

each family confers a number of instance variables (IVs)

for example EnemiesFamily has an IV "FoundPlayer"

and MovingObjectsFamily has IV "IsMoving"

Now what I would like to do is select by family through family IVs

eg.

Event> EnemiesFamily where FoundPlayer=1

Then SubEvent MovingObjectsFamily where IsMoving = 1

The result would be that the set of objects (in this case the EnemySprites) would be picked that only exists across both these families and satisfy the IV values form each family (eg. FoundPlayer=1(from EnemiesFamily) and IsMoving = 1 (MovingObjectsFamily).

I know I can pick objects from a family using family IVs

and I know I can do this on an individual sprite basis as I have access to all the parent family IV.

But as far as I can see

I cannot do this referencing families directly and picking across families through family IVs.

I have directly solved the problem in my game by combining the families into 1 but I would have rather not have had to do this.

Scirra possible something like this could be made work?