SLP Question

Hello Symantec Forums! Have (hopefully) a quick and easy question to answer.

Background

NBU 7.6.0.2 Master

NBU 7.6.0.2 Media

DD4200

2xDD670

I have two SLP policies (full & incr).

I am currently duplicating the Fulls from the 4200 to 670s (load balance setup)

I have run into a storage constraint on 670s (suprise suprise). My question is, if I modify the SLP policy to lower the fixed retention which duplicates Fulls from the 4200 to the 670s, will that apply to existing backup images on the 670s?