many ideas here re grouping or saving texts to special folders, but they mention work vs personal contacts; no, please do not automate based on contacts. or perhaps this could be an option to my clarification, which I believe serves your user base more completely.

Let us define and name (1..10?) folders. We then copy texts to these folders. Each folder having move/ delete|highlight [select|all] texts/ delete folder.
keep simple, sort texts in ea based on date/time as now in one-for-all.
E.g., I am currently looking for a new apartment to rent; I don't know the contacts, but I want to keep these grouped together. it isn't work, it isn't personal.

Many such weeks long projects pop up that I and others could use this functionality to better organize, then clear these safely when done, leaving work and personal texts wherever they are, in main list or another defined folder.