The inspectorate is proposing that all VAAs receive a single judgment following an inspection that should take place every three years, irrespective of the number of branches they have.
Under the current arrangements all VAAs must notify the inspectorate when they have a new manager at a branch, which is then subject to a separate inspection.
In its response to the plans, UK-wide agency Coram says inspection judgments still need to reflect local differences to give a more accurate picture of an agency's performance.
The agency says that where a branch runs a separate adoption panel and has distinct local recruitment and assessment operations it should still be subject to its own inspection.
However, Coram acknowledges that if there are no such differences a separate branch inspection would be unnecessary.
"It would be unhelpful to potential adopters who use Ofsted ratings as a basis for selecting an agency, if the global rating of a VAA made it difficult to identify branches with particular strengths or those with a particular weak area," said Jeanne Kaniuk, Coram's managing director of adoption services.
"The service offered in one part of the country might be different in many respects from that offered elsewhere."
Also being proposed by Ofsted is that the notice period of inspections is cut from 10 working days to two.
Coram is concerned this doesn't give enough time for agencies to fully involve adopters and children.
"This period of notice does not allow time to arrange a programme of meetings with adopters, adopted children and others. It also disadvantages small VAAs with a flat management structure," Kaniuk added.
"If the director is on leave and the manager is perhaps taken ill, there might not be time to arrange management cover to organise the inspection and support the inspectors and staff through the process."
A consultation around the proposals closed earlier this month and Ofsted is now considering the findings.
In its consultation documents, Ofsted states that VAAs had said that inspecting additional premises leads to duplication of work and is deterring some from opening new branches.