Merging

During the first attack in a recent battle, my phalanxes just got flanked and each is now at half strength. So is it possible to merge them whilst on the battlefield?

As far as I know, no. Anyway it is better usually to retrain them after;

but what it have to do with modding questions? Colosseum is exactly place for this..

Not a modding answer, but you could put them into a line together and group them.