Health & Care Visa Extension: Applying without CoS due to UKVI allocation delay

[Coopnext]

Dear Members,
​I am currently in the UK on a Health and Care Worker visa as a Care Assistant. My current visa is expiring on 14th July.
​My employer wants to extend my sponsorship, but they are currently facing delays. They have already submitted an online request to the Home Office for an additional undefined CoS allocation, but it has not been granted yet.
​My employer told me that under the UKVI Caseworker Guidance, if the delay is on the Home Office side, the caseworker will hold the application. They advised me to submit my visa extension before 14th July without the CoS to protect my Section 3C leave, and then delay booking my biometrics for up to 45 days while we wait for the allocation.
​I am planning to submit this application myself,but I want to make absolutely sure I follow the correct procedure. Could you please advise on the following:

​1.What should I type in the mandatory CoS number field?

2.​If the CoS arrives within the 45-day biometric window, what is the best way to submit it? Should I just upload the CoS document to the UKVCAS portal before my appointment?

3.​If the CoS does NOT arrive within 45 days, what supporting documents should I upload for my biometric appointment? My employer will provide a letter confirming their pending allocation request reference. Is this sufficient to prompt the caseworker to hold the case?

4.​If the CoS arrives after my biometric appointment has been completed, how can the CoS details be linked to my application?

​I would be incredibly grateful for your guidance, timelines, or any similar experiences from members who have successfully navigated this.
​Thank you in advance for your time and help.