Upgrade question: Inheriting a new parent

Support Contracts
1

Is there any danger of storage collisions when as part of an upgrade, I add a new parent contract (which has storage variables) to my implementation?

Specifically, I want to add AccessControlEnumerableUpgradeable.sol

The tests are passing but I'm nervous about hidden bugs that won't crop up until more data is stored in the proxies.

2

Are you using OpenZeppelin Upgrades Plugins to check for storage compatibility?

If your contract has storage variables and you add a new parent contract with storage variables, it will definitely corrupt your layout.

contract P {
    uint x;
}

contract V1 {
    uint y;
}

contract V2 is P {
    uint y;
}

Upgrading from V1 to V2 would corrupt the storage.