I have 30 years of experience with databases in my company. For 20 years we used the same field for multiple purposes when a new purpose was to be rarely used. It was OK when we had HDDs with 500MB. Over time our databases became bigger and bigger, with hundreds of tables and fields. About 10 years ago we realized it is increasingly harder to maintain programs, and especially write updates of database structure because of this practice. 
Since then we add new fields for new data. We still have not managed to update all multiple usages, and it has been 10 years.
I strongly recommend you add new fields for new data.