Detail field in "Pending" & "Waiting on Third Party/Customer"

Currently, when we're waiting to receive a part or must do one task prior to starting ticket, we can select "Pending".  It would be great to have a field to indicate what we are waiting for.  When I select "Pending" from the drop down menu, a text box would appear, where I could enter either plain text ("parts delivery") or a pre-existing ticket number, which would pull up a link to the corresponding ticket.  That tells other agents, and possibly customers, what the reason is for not starting the task immediately.

If entering a pre-existing ticket number, that corresponding ticket should then receive an update to say that other tickets are backed up until this one is completed.  For example, the ticket to install a new VOIP phone in a room must wait until the ticket for installing the new POE switch is installed.  The VOIP ticket wouldn't begin to "start" until the POE ticket is resolved, because it's impossible to do one until the other is completed.

Similar to entering a ticket number, a text box could appear for "Waiting on Third Party/Customer", where I can enter an agent, customer or an email address.  If they are in the system, it pulls up a link to their profile, just as entering names into the "Requester" field does.  They can also be notified when this ticket is saved.  If they are not in the system, it will still be displayed in plain text.  That could be useful when you don't need to notify anyone, but want agents to be aware that you're "Waiting on Third Party: Lenovo Support", for example.