What can I do about a co-worker that has extreme absences, filed an FMLA and is now pregnant?

3 union employees doing the same job (a sit down clerical position). The subject employee has had absenteeism problems for years and blows through her vacation time early in the year then just calls off sick or just needs days for whatever personal matter she has going. The "timekeeper" was her aunt and did not record most of her absences. I am now the timekeeper and keep accurate track of all employees in the dept. I brought her extreme time off to the attention of our boss (who does not like conflict) and HR. When they finally addressed the situation, the subject employee immediately filed for FMLA for migraines, used some FMLA time off for same but that became costly so she hasn't taken FMLA time off in more than a month after she filed. Now she announced she is 7.5 weeks pregnant and missed 3 days of work last week for "illness" (not sure if pregnancy related or just sick as my boss called it illness but the employee told us she has a hematoma so she has to take it easy). She obviously has no sick time or vacation time available until the beginning of 2019. It appears she will do whatever to keep her job and her paycheck whole and it appears she is being successful. The whole situation has caused extreme tension in the department because we abide by company rules and she gets far more paid or excused time off than she works. We are witness to her conversations about her weekend activities (weekends are always migraine free) and complaints about having to be at work when she has "something so important going on" in her life. Of course she will get sick to accommodate that stuff but it will not be FMLA related. Is there anything we can do as union employees that will not interfere with her FMLA or be considered pregnancy discrimination. The union has not been involved in this as I believed HR and my boss would handle it (that is tell her to show up for work and work for the paycheck she continues to receive) - yet I see this employee has figured out how to get around the system to maintain her employment but not work. She's been doing it for years at one point having 165 days absent in one year not including vacation time. To top it all off she shows up 1+ hours late every day, takes 1-2 hrs. for lunch and leaves at 4:00 every day - that is she works maybe 6 hours of an 8-hour day. I am required to give her time record to my boss each week, but this behavior doesn't seem to be addressed as it continues week after week. I have a few questions: How do we deal with this as co-workers that abide by company rules? Can we protest in any way without being penalized? How much do we have to suck up and deal with? What rules does she have to abide by in order to keep up this BS? And what can we do to call her bluff at any point or file a legitimate claim to make her change this behavior or be terminated. She is never going to change given past years' practice but since it has caught up with her she is finding legal ways to protect herself.