An apparatus for forming stacked article groups in a packaging process, comprising a linear conveyance mechanism having an upstream end and a downstream end; and at least one article input and combining station, the article input and combining station including high and low article input lines and a combining wheel, the combining wheel being disposed tangentially with respect to the conveyance mechanism and further being arranged to receive a high single level article group from the high input line and to transport the high single level article group to a point of intersection with the conveyance mechanism, the low article input line intersecting the conveyance mechanism at a position which is located upstream with respect to the intersection point and depositing a low single level article group on the conveyance mechanism, and wherein the combining wheel merges the high and low single level article groups to form the stacked article group at the intersection point.