§1. Works which a diocesan bishop entrusts to religious are subject to the authority and direction of the same bishop, without prejudice to the right of religious superiors according to the norm of can. 678, §§2 and 3.
§2. In these cases, the diocesan bishop and the competent superior of the institute are to draw up a written agreement which, among other things, is to define expressly and accurately those things which pertain to the work to be accomplished, the members to be devoted to it, and economic matters.
Source: Code of Canon Law (Vatican.va)