The second focus of this work is to suggest the integration of the strategic molecules in pathway screening when new chemical processes are developed or, more specifically, an alternative feedstock is sought to produce a known product. A chemical multi-step synthesis from a feedstock to an end product can be resembled by a path in a network from the feedstock node to the end product node. Assembling all sets of the possible paths is commonly done by a screening method, for example depth-first (DF) screening. The total number of paths scales with O(N!) where N is the number of nodes in the screening set and the algorithm has a time complexity of O(N+E). In this work we propose to include strategic molecules into screening algorithms. We combine a DF search as implemented in Ref 54 from feedstock components to strategic molecules with a DF search from strategic molecules to end products. We call this approach reduced-path depth-first (RPDF) search. We constrain the maximal search depth for both the DF and the RPDF search by cut-off values. A cut-off of one means that only one reaction step from the starting molecules is permitted, a cut-off of two allows two reaction steps and so forth.