You can create as many precipitate removal mass flux links as desired in order to build your pathway network. There is, however, one limitation that you must keep in mind regarding the use of these mass flux links: Precipitate removal mass flux links are uni-directional. That is, mass can only flow in one direction (negative transfer rates are not allowed). If you wish to simulate a reversal of the transfer direction, you must create two separate precipitate removal flux links to represent this (one flowing in one direction, and the other flowing in the other, with the transfer rates defined using expressions which ensure that they are never negative).