You can play RTW through the BI.exe so you don't need to move units around

see https://forums.totalwar.org/vb/showp...tcount=1219905
for how to set that up.

Then follow instructions above about adding can_swim to RTW units.

Only other things you might need are BI animations moved to RTW folder (not sure on that one) and adjustments to UI interface to get the logo for swimming.



It would be better and easier if you set up your game in mod-folder and make all the changes in that.