Two dog help

Hi I’m just wondering if I’m missing anything to help two dogs live together
Both were rescued

The eldest is actually nearly three bichon mix but looks and acts much older
Is happy ,to have one or two ten minutes walks and likes to lie and laze, is not a morning dog can be moody with younfshe’s had resource guarding issues all her life worst at 6-12 month and has had behaviouralist training done and is so much better but I’d still not trust ever with my kids and other dogs

other dog is nearly one year old took her in off an elderly neighbour had her six or seven months now, she’s a Jackapoo so very lively bouncy but full of fun very clownish and so so soft , I’ve seen nothing but love come from from this dog she’s such a happy go lucky friendly puppy.

so older dog seems quite bullying to pup if they come across each other she’ll pounce and pin down and shows her teeth a lot

pup seems unfazed by this but is submissive she bows and licks older dogs face as she’s snarling at her

of course I intervene and seperate they sleep and are now mainly seperate
In seperate rooms, feed seper

I do walk together but old one mainly ignores the pup and pup does settle down after five minutes

it is exhausting though as I feel on edge I’m pregnant and have young children so what can I do to make it better? Will they always need to be seperate should I not even try to bring them together? As older dog just seems moody and grouchy and I hear growl a lot
If anyone has any other suggestions or ideas I’d be keen to hear and try