Modify standard fit models to force intercept at [0,0]

Hello,

I know I could probably just use a custom fit to solve the problem I have right now, but I want to know if it is possible to modify/create a fitmodel after the library models, f.e. 'poly1', but force it to intersect at [0,0]. As far as I know, I could achieve this by just fitting 'm*x' in this case instead of poly1, but is there a way to apply this to all fitmodels? or would I have to create corresponding strings missing the constant term at the end for achieving this for every model?

Thank you & stay healthy

Claudius Appel