sorry. I have dyslexia, I just installed Grammarly on my web browser so I didn't even check but I guess it's not as good as it claims. I will repost with correct spelling since it will not let me edit it

sorry. I have dyslexia, I just installed Grammarly on my web browser so I didn't even check but I guess it's not as good as it claims. I will repost with correct spelling since it will not let me edit it

Previously I have failed a couple of times to secure a second supervisor because I wish to write and illustrate a children's book about visual illusions. When I applied to do a practice-based illustration PhD they said they did not have a second supervisor with knowledge of this subject in the art or any other department including phycology.
So I have now found a uni with experts in visual illusion in their phycology department, but I do not want to study the phycology of illusions on children. I wish to create a book of my own interpretations of visual illusions (for children) on a practice-based PhD.
So I think I should approach the children's creative writing/ illustration supervisor in the art department to find out if I could do a practice-based PhD first.
But I think like the supervisor I approached before he will say it's not his area of expertise and/or interest.
So I'm wondering if I should try it the other way around this time. Should I approach the expert in visual illusions in the phycology department and say I want to do a book about illusions and have him as the 1st supervisor and the children's book expert as the second supervisor.

Is this possible? Or do 1st supervisors have to be in your area of expertise and proposed outcome? (I studied art not phycology for BA&MA)