A contract was awarded for a base period of 6 months and an option period of 6 months for severable services. The 52.217-8 clause was included. After the base period ended, the 52.217-8 clause was used for an extension of 3 months with no other changes to the contract, the -8 clause was used again to extend for an additional month with no other changes to the contract. The 6 month option was exercised and five months into the performance period of the option, a scope change was required which caused the contractor to purchase additional supplies and required additional lead time and so the Changes Clause (52.243-1 Alternate II) was used for the within scope change and the contractor was granted an extension of 3 months. The 3 month extension has ended and we would like to use the -8 clause again for 2 months (the -8 clause was previously used as an authority for a total of 4 months out of the 6 allowed). Did the use of the Changes clause negate any time being left on the -8 clause or is an extension of 2 months still permitted using the -8 clause?