I have a couple of examples of this

My friends dogs when the pup came along the older dog just took toys off of her, friends thought this was cute 0 older dog was being the 'daddy'
Result is now that the younger dog is V agressive and protective when she has something - she has learnt if a dog comes near her she will loose the item she prizes - so she just launces attacks at any dog anywhere near her

Mia came to me and would launch attacks at Ben if she had anything - or if he had anything
Not just a spat and it had to be broken up - one time we had to pry her jaws off of Ben face (she didnt hurt him - I think it was just a mexican standoff - If I let go of you you might go for me so I cant back off)
I worked on the principle that whoever has the object owns the object - you are safe with what you have - unless you choose to give it up

Training was in several steps
limiting toys and chew and things unless I was 100% supervising - and distracting Mia if she focused on Ben - also rewarding her lots when she was near Ben and he had something - so she got used to nice things happening when she was around Ben
If she did get too fixated on Ben and the toy I just calmly put her in her crate for a time out - brought her out again and then rewarded her for being calm
I also spent lots of time treating them together - treats at the same time then one for Ben and one for Mia a split second later. I also chucked some treats on the floor for Mia and while she was munching them a little way off I chucked less treats on the ground for Ben - so she got used to him eating treats close to him - but he was finnished before her so she had no temptation to go for his

Thankfully it worked
Now if Ben has a toy and she wants it she offers her cutest tricks to ask for the toy, Ben is happy and safe enough to continue chewing his toy with her right up in his face rolling on her back and trying to be cute. Sometimes he does let her have the toy - and then she slaps it back in his face for a fun game to happen
I can also scatter treats on the floor and they happily snuffle about eating them up without bothering each other at all.

As Wys said - I dont know your situation 100% and you know your dogs better than anyone so you know what is best for them - that is just my experience