Feature request: authorize delegation to specific user

Hi,

We are currently having some issues with the delegate feature.

If we allow the delegation of signatures, the sender has zero control over who signs the document when the receiver of the document delegates it to someone else.

Can we please get a feature that if a requested signer delegates the document to someone else that the initial sender receives an approval task for this? This way we stay in control of the document and ensure the document isn't completed with (for example) the signature of a secretary who isn't even allowed to sign contracts. 

In case of a rejection or as an alternative as sender it really should be possible to delegate a specific signature field to someone else to avoid a document ends up unfinished when the original indicated signer is no longer available.

I hope you'll take this into consideration!