Seamus McAleavey, chief executive of the Northern Ireland Council for Voluntary Action, said: "The public benefit test is a cornerstone of the legislation. We would not like the commission or any other body to make changes that could have a huge impact."
These concerns were shared by CO3, the chief executives organisation, and the Volunteer Development Agency. Nicva and CO3 also said the Northern Ireland regulator should limit its publication of guidance to avoid conflicts with its regulatory function.
Wendy Osborne, CO3 member and chief executive of the VDA, said: "Tensions will always exist. There are examples in England and Wales of the blurring of the regulatory functions and the advice, guidance and support functions of such commissions, which were no help to those organisations or the charitable sector."
Osborne pointed out that the VDA and Nicva already produced good guidance material. McAleavey said the Northern Irish Commission should produce only regulatory advice.
The Social Development Committee, which published its report last month, welcomed a clause in the bill that would prevent the regulator from removing trustees or appointing interim managers to charities with special designated religious status, saying they already had internal governance structures to deal with investigations and suspensions.
The bill is expected to become law by July.