Is it okay to refill waterman pen with parker refill?

I have a waterman pen that needs to be refilled soon. I use the waterman standard ballpoint refill. Recently I noticed that parker pen refills are much cheaper. Is it alright to use them instead? Are they even compatible? Thanks!|||I used waterman refill on mont blanc pen. The refill is similar in size so I have no problems. Hope this helps!|||I doubt it if Parkers will fit the Waterman pens. If the refills have the same length and configuration as the original ons, maybe.