Can an employer alter Sectional Completion requirements once in Contract? What are the potential impacts on section damages?

Can an employer omit works from one Section of works and add them to a later Section (e.g. Omit works from Section 3 and Add them to Section 4). Essentially redefining the sections set in contract.

The reason for the potential change is the employer had not realised some of the works in Section 3 were dependent on services which can’t be provided until completion of Section 4 (hence desire to add them to section 4). Partial possession of Section could be achieved by moving works to section 4. Contractor is already late in Section 3 and on the end of substantial damages, insists sections cannot be redefined and moved from one section to another. Essentially arguing any omitted works, when added back, must be eventually added back into the original section (i.e. Section 3 not section 4). Thus becoming a variation preventing the full handover of section 3 (providing potential EOT, or at very least alleviation from damages).

What’s the contractual / legal impact on damages etc.