This is straight from the LOA, it sucks what they’re doing but doesn’t seem like they are violating it. Doubt the union will win grievance.

Upon delivery of the 40th EMB-175 as set forth in Appendix D, and assuming there are still pilots who were added to the Envoy master seniority list on or before October 11, 2011 who have not yet been offered a flow through opportunity, 50% of all AA new hire training slots, no fewer than 25 per month (subject to the 50%), shall go to such Envoy pilots, until the point in time when the next pilot on the Envoy master seniority list to be offered a flow through opportunity was hired after October 11, 2011.