Rule reminder
Dal momento che ('from the moment that / since / given that') is a formal-neutral causal conjunction. It presents the cause as a definitive, often chronological or logical turning point. It takes the indicative and can appear before or after the main clause. Register: slightly more formal than 'visto che', less formal than 'poiché'. In formal correspondence it is very common.
Siamo disposti a rinegoziare _____ le circostanze sono cambiate.