Date: 202011
Local time of day: 1801-2400
Location: ZZZ.ARTCC, US
Aircraft: Military
Operator: Military
Operating under: Part 91
Flight plan: IFR
Mission: Training
Flight phase: Descent
Airspace: Class E ZZZ
ATC / advisory: Center ZZZ
Second aircraft: Military
Reporter organization: Government
Reporter function: Handoff / Assist; Enroute
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Communication Breakdown
Anomaly: ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Automation Air Traffic Control; Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Provided Assistance
Contributing factors: Procedure; Airspace Structure; Environment - Non Weather Related; Human Factors
Primary problem: Procedure

Narrative: I was paged back to work the D side on Sector X to assist the Radar Controller. The previous evening we were told that we had to take over ZZZ TRACON airspace because they had too many COVID cases to staff it properly. We have been working without any clear guidelines and it feels like every shift when we come in we get new information about what we're gonna do and how to work aircraft in and out of this airspace without any training.  While having to work Sector X and ZZZ TRACON airspace; he got request from Aircraft X to do a flyby at Park X and University X. He then started getting requests from Aircraft Y and Aircraft Z to also do those without any flight plans. Controller Y was working a light to moderate workload until all of these requests came in. Because we had no information about the flybys; (there was actual information offered to ZZZ TRACON; but they did not share it until we complained). This session became extremely confusing. I was attempting to coordinate with ZZZ Tower about them coming in bound; but they were staying above their space.  Our side kept giving them communication changes over to the Tower and then they were being sent back. Luckily no incident occurred but this made for an extremely high workload and high stress scenario. Because of the confusion at the sector I had a very difficult time even being able to help from the D side. The more information we have ahead of time the better. But having zero information was really difficult to manage with the increased workload of our own airspace and TRACON's as well.The coordination between TRACON and our Center requiring that we take over this airspace for two weeks has been very poor. The supervisors and operation manager on duty have attempted to coordinate for us; but with every day I walk in; we get new information about how we have to change what we had done the day before or what we were doing was wrong. This also leads to controllers in charge being responsible for the area much more this week than normal. We needed the support of our airspace and procedures staff to step in and get some coordination done to give us clear guidance as to what we should be doing because our LOA with TRACON does not clearly cover how we take over their space. There's been confusion all week as to whether they are Class C surface area or a Class D. Also; they have a waiver to be within 1 mile of a restricted airspace RXXXX while fixed wing aircraft are in the space. They've been in there operating all week long while we've been doing mostly visual approaches but sometimes IFR approaches. But apparently some of the IFR approaches are not separated from the restricted airspace. Which creates a very unsafe situation for us to take over the space with no training. We also need any of the flyby information passed to us. We now have that information; but we didn't until date; one week after taking over their airspace. If we had the information about the flyover; the session would not have been nearly as stressful and confusing. And my XX years here I've never been so confused on sector. Luckily; he was not overwhelmingly busy with his other traffic.




Synopsis: Center Controller reported confusion with taking over a TRACON's airspace and difficulty with coordination with Tower on how to handle some flights.