Thank you! We did have them meet before bringing new girl home, we walked them together several days in a row so they could get used to each other. Since having them we've made sure to give them 4 walks together a day, some short some longer. There has only been the one fight on day one, the other growls have been if they've both tried to squeeze through a doorway together or 1 has gone near the other when on a bed. We recorded them last night and it was literally one minute of growling and barking about 2 hours after they'd been put to bed then nothing for the rest of the night (I have no idea what started that) . Son got up early for work and let them out and when we got up they were on a sofa each.
They both wait at the door with waggy tails when we get home, have been in the garden not on a lead wandered up and downstairs mostly without issue. They will lie in the same room on beds etc
I'm just watching our original girl closely as she loves playing with toys and wandering the house following us but hasn't really left our bed or been able to play with her toys with the muzzle on and has been a bit hesitant of going in the same room as new girl at times!
It is very early days and I'm hoping they will figure things out I just wondered how long we should ideally give it - so thank you for your advice!