Part one of this memorandum provides a summary of questions asked and comments submitted in response to the DOL request for information ("RFI") about waiver of FMLA rights.
Part two of this memorandum contains the relevant statutory and regulatory text. Part two also lists other sources cited in the comments about this topic.
Workplace Flexibility 2010, Georgetown University Law Center, "Waiver of Rights" (2007). Memos and Fact Sheets. 41.