Polish to English Social Sciences History

18th century history book on the Order of Malta - this section discusses how members of the Order can obtain Commanderies (Komendorstwa - a territory under the control of a commander of an order of knights, originally only the Knights Hospitaller).

'It is permitted to choose and receive a Commandery d’échévissement, and even one that has already been granted to someone else. Said Commandery is retained as a result of performing a first amelioration, and after five years and a further amelioration, it is possible to choose yet another Commandery as a result of performing the second amelioration. Przy każdey zamianie czyni się pospolicie protestacya, że prowent dla prowentu rzuca się, tym sposobem pierwsze Komendorstwo nie traci się, ieżeliby zabiegi i starania względem nabycia drugiego bezskutczne zostały.'

The part I'm really struggling with here is 'prowent dla prowentu rzuca się.'

Any suggestions would be much appreciated!