Can someone change PhD supervisor without changing research direction? Background: My supervisor wants to quit my supervision due to reasons beyond his control. He suggested few colleagues to replace him. My only concern is that I be asked to switch my current research direction to meet that of my potential new supervisor. I have spent considerable amount of reading and review, designing simualtors and coming up with new ideas and I don't want to restart all over. I found a co-supervisor who is closely related to my field and agreed on supervision (He is not affiliated with my university anymore though), but still need a main supervisor. 

Question: Am I obliged to restart over and lose all my reserach?
The few times I've seen this happen, usually the new advisor in your home department is willing to let one continue on with the same research project. Beware that you'll have less support from your advisor than you might have had otherwise, but if you have strong people in the field outside your university,  as it sounds like you do, then you should be ok. Another thing to beware is that your advisor's letter of recommendation is going to be crucial if you apply for postdocs or other academic positions down the line. Having your advisor not really know your field, or understand your work in depth is likely going to lead to a much shallower, less effective letter simply because your new advisor won't be able to speak with the same degree of knowledge about what exactly your contribution is. 

So, you're going to have to weight these two potential cons against the cost in time and effort of simply starting over from scratch with a new advisor.