As explained on the other thread, this is not a "joint" IVA, but two interlocking IVA's. Each is an arrangement in it's own right.
You need to convince GT to separate the IVA's (which they do not like doing, but is an operation they are capable of doing very easily). Then each of you is free to do with your own arrangements what you will.
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014