How fees are deducted from multiple sender's transaction

If there are multiple sender’s in one transaction, how the fees are getting divided between them? equally? or how to identify?

That’s something you decide. The sum of all inputs - outputs - fees must be zero. The refund address is one of the outputs.

I’m not using it. I want to integrate it with my application so from APIs/explorer I’ve to find from which account fees are deducted.
Is there no way to find it?

The thing that creates, signs and sends the Tx chooses the refund address. Do you not control that thing?