Q: Can you explain the LOAs at the end of the contract – can the company extinguish?
No, a Letter of Agreement (LOA) has the full force and effect as the contract. Some are kept as LOAs as they have a separate expiration date/sunset clause, or only apply for a certain period of time.
Some have controversial genesis – sick family/sick child has been an LOA for a long time, but it was a long fight over the years with management. It has the same effect as contract body text, but management is resistant to putting this language in the actual body of the collective bargaining agreement. Regardless of the reasoning for keeping a provision as an LOA rather than in the body of the contract, it still has the same effect and force of contract.