Squared coupling orders and MadSpin

Hi,

we are trying to generate a BSM sample using squared coupling constraints, for example
'p p > j j w+ w $ t t~ NP^2==1'
and would then like to decay the bosons using MadSpin.

Our understanding is that this might result in the correct physics, as the new-physics coupling only affects the quartic gauge coupling but not the decay. This approach does not work out of the box with MadGraph (we encountered an error: "Decay processes cannot specify squared orders constraints") but we found a workaround from question 255413, one can make it run if the NP^2 is simply removed from the LHE file before MadSpin is run.

Are we right to expect this gives reasonable results or is there something we are missing?

Cheers,
Hannes