Bodywork experts!

I wouldn't try to move the 1/4s. I would take a cut off wheel and make a cut off each end of the valance.

Remove the material from the valance as needed (should only be a little bit).

Get everything clamped into place ON THE CAR.

Tack weld then carefully stitch weld the cuts back together. Do this slowly allowing each tack weld to cool.

Once the welding is done grind the welds down, hammer and dolly as needed, finish with body filler.