Inserting systems and methods are provided for use in sheet processing. The inserting systems and methods provide improved handling of sheet articles during processing. Sheet articles can be advantageously and efficiently advanced in separate stacks and later combined for insertion into an envelope. For insertion into an envelope, the mouth of the envelope can be selectively variably opened depending upon the amount of insertion material to go into the envelope where the amount an envelope is to be opened can be based upon processing or job information. Sheet articles can be registered and aligned to facilitate processing efficiencies. Sheet articles with creases, such as envelopes with mouth flaps, can be processed through a roller system to bend the crease so that the flap of the envelope assumes a desired position for subsequent processing. Additionally, sheet articles can be processed through a staging station with increased capacity for sheet processing.