Hi Tony.
No,i don't believe that you need to prove ownership of the donor parts.
As many peole wish to obtain an age related number plate for their build the most simple method is to provide your local DVLA with the donor cars V5 document.
It is then easy for them to check that the parts used came from a single donor.
I believe the best way to do this is to obtain a V5 in your name & keep the donor vehicle on SORN until you are ready to register your build.
As you are going for a Q plate you should have no problems. The donor parts can be a mixture of parts from many different cars.
I would avise that you keep any reciepts for the parts bought though.
One possible issue may be proving the age of the engine.
There is some talk about this subject. It would appear that, if you cannot provide proof of you engines age, your build will have to meet the latest emission regs.
Some people have used Burton powers engine build code list to prove the build date. Others have written to Ford for engine date confirmation.
I think it is simply a matter of how your local DVLA work & how anal they are.
I am by no means an expert in this area. This is just my personal take on things.
I am sure that I will be corrected if I am wrong.
