Answered: NEC3 ECC: Can the Employer use the works past the Completion Date but before Completion?

It could be a compensation event under 60.1 (5), but the circumstances would have to much the bullet points in in 60.1 (5). There is not enough detail in your question to answer this, but use of the word "work" in all three bullet points implies they are doing something to the works, rather than using it.