[gmx-users] Force fields

[Alex]

Dear all,
I have the Gromos-54A7 force fields (FF) for the molecule number 1 in the
below link, using thoes how I can have the FF for the molecules number 2,3
and 4 in the same link without doing extra calculations? What could be the
relation between the FF of other molecule with the FF of molecule number 1?
Molecules 2,3 and 4 are the output of a kind of condensation reaction
happening between two number 1 molecule in sequence.

https://drive.google.com/open?id=1zqLSSdtDHrdVMO567WFSavAiVN-knLuX

Thank you.
Regards,
Alex