a is the contract that contains the delegate call, b is the calling contract,
I wonder if this B contract can be used for another contract also which contains delegate call?
In the end, I'm interested in how in this case contract B should be made in accordance with contract A to call delegatecall, what should I take into account? and if the same contract B calls another contract that contains delegatecall, What should I change in contract B?
I suggest you to take a look a the diamond structure where you define one main contract that will delegatecall to the right contracts depending on the function signature https://eips.ethereum.org/EIPS/eip-2535
Otherwise concerning your questions, the main thing to take into account is storage collision, contract A delegateCall to contract B will modify contract A storage. You can add a check inside contract B depending if you want to delegateCall to another contract, based on the Diamond structure, one way to do so is to define a function signature with contract addresses to delegateCall to the right contract.
