Hello Reynaldo ,
In EKKO there are 3 importanat fields related to Release Strategy which are as follows :
FRGGR Release group
FRGSX Release Strategy
FRGKE Release Indicato
Out of these three the first one is Rlease Group and to each Release Group Release Strategy is maintained.
And inside these Release Strategy the real STRATEGY is defined.
If a PO is subjected to Release Strategy then value of these fields cannot be INITIAL.
You can check with this condition and implement a suitable EXIT or BADI.
But the purpose of you requirement is still not clear.