@Tvoj-Host0
I don't believe there is a way to do this. Airbnb needs to verify a phone number for each owner's listing and they also verify the address. They don't allow the same primary phone number for multiple listings or profiles as far as I know. You can contact Airbnb CS, but I fear you may get different answers depending on who you talk to.
I suggest you explain to each owner that Airbnb requires an initial phone number verification and they will get a request to verify their phone number when the listing is created. Then the owner can turn OFF notifications on their Account Settings, if they don't want to receive the guest messages and only want you to handle that. When you have full access Co-Host status, then you can be named as "Primary Host" and will show as "Host" to the guests with the owner as Co Host. The owner's still are shown as Listing Owner on the account, but show as "Co-Host" to guests.
What Co Hosts Can Do
https://www.airbnb.com/help/article/1534