Rest API warm transfer and convert calls to conference

Hi there,

1. User1 is connected on the caller.
2. User1 make a consultation call to User2.
3. User1 "CompleteTransfer" or "Conference" on 2 calls using Rest API.

Can we complete transfer on 2 calls? is the bridge API https://developers.ringcentral.com/api-reference/Call-Control/bridgeCallParty we should use?

Can we conference on 2 calls? I cannot find any API for that. Is is supported?

Any help is appreciated!

Josie