How can we do a Mass Change of Bill To on Contract Lines

The various hospital NHS Trusts are starting to use a central accounting service.  Obviously as the hospitals change over we need to change the Bill To address for the hospital. 

However we have many contracts with that hospitals that involve regular billing.

If we run the Contract Mass Change for the Bill To address, this only updates the hospital's contract headers.  It does not update the Bill To on the contract lines. 

The Contracts billing process uses the Bill To on the lines so is there some way we can automatically change the Bill To address not only on the contract header but also on the lines