tobee The EU have repeatedly said they won't renegotiate the WA
They mean it, because weakening the backstop - which is the sticking point - would mean
either dumping Ireland - and wrecking the EU politically
or damaging the Single Market - and wrecking the EU economically
i.e. worse for the EU than No Deal
After Brexit, the main terms of the WA - esepcially the exit bill calculations, expat rights & backstop - will be put in another legal document
(called maybe "Memorandum of Understanding xxxx")
which the UK will have to sign and pass in the HoC before negotiations on even mini-deals can start