Not entirely sure what you mean by this so some further information might be helpful but as a general rule, decisions of a town or parish council can only be made in a properly constituted meeting, i.e. one where the minimum of three clear days notice has been given, the agenda and supporting papers have been published and the public have access. That doesn't mean to say that task and finish groups, etc. or informal discussions can't take place but no decisions can be made at those meetings.