No. Managing trustees may ask for reimbursement of reasonable expenses but must never carry out work for their church on a paid basis because there is a clear conflict of interest, while this is also contrary to charity law.
If you appointed either of these people then it could be very embarrassing for all concerned if problems occurred due to bad advice and you (the other managing trustees) were forced to take legal action. It is very important to remember that verbal and even unpaid advice carries the same liability as it would if it were paid for. We therefore recommend that you do not consult either person and instead seek independent professional advice from an external architect.