It is actually a rather common thing in my Rps. Many of the rpers in them have characters they have played in the past and continued their story line into one of my Rps or even to another of mine once it finishes. We have a good dozen that have been in at least 2 rps, some that have been in 3. A couple that have hit their 2nd RP and even one that is on their 5th in a row to just to continue the story line. 

	I actually have 1 rp that is devoted to a characters "second chance" after death so that whole cast is nothing but a continuation in a new light. It can get rather complex as people have broadened out to other Rps outside of mine and we have done cross Gm tie in to other whole story lines. It has created a very wonderful dynamic in the over all group to have so many tie in's, back story's, people their characters can meet that know of other characters, even family lines that cover hundreds of years and dozens of RP's. Some even break off to 1x1 privately to build up back story during a time jump or down time in an RP. 

	It might not be a common practice but it is out there and thriving.