New rescue advice

[Allfurcoatandnoknickers]

I’ve got a 7yo JRT Cross female and have just adopted a second 2yo male. We’ve had him for two weeks. For the first week she was ambivalent towards him, since then they’ve been getting on really well and been playing together loads. I’ve just been sat on the sofa trying to stroke them both and they started to play- lots of mouthing. It then seemed to escalate into a spat. They were separated and sent to their beds. They’re quiet now and settled.
I feel a bit worried that this could happen again, and also sad that they might not get on.
I’m not sure if there was some jealousy going on in the older dog as I was sat with them, if it was her testing the water or a sibling type of spat?!
Any advice appreciated 😊

Talk to the people you got the dog from, some dogs get along some won't any new dog should have a return ticket just in case, sadly so many breeders don't think like this.
Talk to a trainer/ support group

I read some advice recently and one thing that stuck was, to favour the original dog. By which I mean, feed her first, give her the treat first etc.
I rehomed a second lab a while ago and we had some spats initially always with dog2 launching herself at dog1 ; I had to show them both that I would not tolerate that - if she stole a toy I had handed to him, I took it from her and gave it back to him.
My vet said that if they could sleep in the same space ( with me in the room) then they would settle, and that’s been the case ( I didn’t leave them alone in the same space for a couple of weeks)
So yes , there probably is some jealousy, some competition going on, but they can probably get through it, especially if different sexes.
You did a nice thing, I hope it works for you.