How to delete file with sharing with expiry date from Thunderbird

[Kano]

Hi all,
I have Nextcloud set up as a cloud for uploading and sharing large attachments for Thunderbird. In NC, a folder is set up that has a tag and anything that is added to this folder by Thunderbird is automatically marked with a special tag using the flow. This works perfectly. But such sharing cannot be eternal, so the TB client has a time limit set for several days. Let’s say 2 weeks. After 2 weeks, NC automatically ends the sharing, but the file remains in the folder.
And then the retention is set so that the file marked with a special tag is deleted after 15 days from creation.
This all works fine.
However, if I send the same file by email just before the sharing of the first email expires, so let’s say on the 10th day from the first email, NC deletes the file in next 5 days, even though I expect it to be active until the 24th day (10+2 weeks).
The problem is that the file is identical, so NC doesn’t differentiate between the two and just extends date of expiration of share.
Some kind of automatic tagging would help when the link expires - but I haven’t found anything like that. Then I could set up retention so that if the file is tagged with a special tag and also a tag that would be assigned when the share ends, the retention would work as expected.
Does anyone have any ideas on how to tag a file when its timeshare expires?
Thanks
Tony