You'll normally have to alter the xover unless the replacement drivers are identical to the original. Madisound should know.
2) BTW, have you tried googling the drivers' part No? It sometimes works.
3) You have contacted Morel, I assume? If not the actual driver, or an equivalent, they may have your driver's TS parametres.
4) Failing the above, try diyaudio.com; someone who has your spkrs may have measured these drivers.