Source: Elines

Our JCBA, section 15.I.6 details the ability for a Lineholder Flight Attendant to pick up from open time when they are able to return to work for a portion of a pairing from which removed for Family Medical Leave. 

"When a Lineholder is able to return to work after a pairing(s) has been removed from her/his schedule due to FML usage, she/he may pick up open time in accordance with Section 7. A Flight Attendant who is able to pick up open time on the day(s) overlapping the removed pairing(s) will have the overlapping days actually worked restored to her/his seventy-eight (78) day FML allocation."

Flight Attendants interested in making up Family Medical Leave (FML) day(s) may do so by utilizing the following procedures:

Contact Crew Scheduling directly to have your Master Schedule updated to remove the overlapping FML code to accommodate the pick-up.

Note:To make up FML on the remaining day(s) of the pairing that was dropped for FML, you must be prepared to let Crew Scheduling know which pairing(s) you would like to pick up from open time at the time of the call. The FML days will not be removed unless, at the same time, a trip from open time is placed on to your line on the day(s) on which you were on FML.