constitional bootstrap

[ShadowWalker]

I'm trying to create an adjustment for the spell Blessed First.
It gives a character improved Unarmed Strike if they don't already have it from some other source.
Is there a way to do a conditional bootstrap that sees if the adjustment is checked or not? i.e. active
if not could someone suggest how best to do this particular adjustment.

[ShadowWalker]

I should correct this after reading the spell description more carefully. It doesn't give the feat, it just gives something similar to the feat.