Its the jointly owned bit that is the problem - see ORS4 no. 803 of 1st july 2010. Instruction for Class Ratings (any licence type) is not allowed - the person undergoing the training must be entitled to act as P1. Sole ownership and it would be OK.
The exemption to allow instruction in a jointly owned PtF aircraft also says it must be carried out in a club environment, I note.
H