Retrospective instructions

On a subcontract under the NEC4 form of subcontract, the Contractor is seeking to issue retrospective instructions for work the Subcontractor has completed but which were not initially verbally instructed. Can this be done? It is for some elements of work in which the Contractor believes the Subcontractor has varied from the Subcontract Scope, but the work has now been completed for some months and there was not written confirmation of any such variance from the Scope in advance of or at the time the work was being completed.

if the relationship between the Contractor and Subcontractor was so trusting that the subcontractor executed a raft of extra work without instruction, then both parties have put themselves in a bad spot.
If the Contractor wants to pass these onto the client, he will suffer issues with time bar.
It would be typical for a contractor to have had to execute additional work and has raised a CE with the Client, hoping to get paid for it.
The Subcontractor may have executed the work for the Contractor on the promise of getting paid.
The Contractor cannot now demonstrate a change to his defined cost, as he hasn’t instructed the work (or paid for it).
This would be a typical MC trick to protect himself from the subcontractor and is now scrambling to try to prove entitlement to the client.

In reality, if the PM or Contractor should have instructed the work because it was a change to the scope. He can now do so, as the time bar doesn’t apply in that scenario.