Can a smart contract bill the RAM storage to another smart contract?

Question

I know that you can bill another user for storage but what if i want to bill another smart contract which in turn will then bill its users. Is it possible?

Answer 1

Yes, as @confused00 mentioned in his comment, you can bill the RAM storage to either the account of the current contract itself (_self) or any account for which the transaction includes permissions. This means it's based on a per-transaction scheme, which means that for example:

1. Account randy submits a transaction signed by his account for an action in contract1
2. contract1 can store something in DB billed to either contract1 account or randy account
3. If contract1 sends an inline action to contract2 then contract2 can store something billed to either contract2 or any of the permissions given in the inline action to it (contract1 or randy)

contract1 can decide what permissions to pass on to contract2 in the inline action.

In the documentation for emplace you can see there's a parameter for defining who is billed for the storage: https://developers.eos.io/eosio-cpp/reference#emplace

In the documentation for inline actions and permission levels you can see how to send actions and set the permissions: https://developers.eos.io/eosio-cpp/reference#structeosio_1_1permission__level

EDIT: Also more related information here: How to authorize inline action of another contract within a contract?