Absolutely, evil- I totally get where you're coming from, but, for the sake of backing up what I said, a person is off my team because of stress right now; My team consist of 6 people, and, like you, I can't reschedule my workload- patients still need their diagnostic tests and we get heavily fined if any 'breach' so we don't have the 'stick 'em with a supply teacher' option! At DSs' high achieving comp, my DSs are in what's called 'canteen cover' at least twice a week each, where one teacher sits, supervising up to 90 DC in the canteen, DC whose regular teacher is sick or absent for another reason. He doesn't 'teach', he supervises and the DC must maintain absolute silence throughout, doing pre-set work.
As a result of this person being off, instead of being 'on-call' 1:6, it's 1:5. That means that, with 20 minutes notice, maybe at 3 a.m, having already worked 9 odd hours that day (and due to do the same again tomorrow) I have to be up, dressed, capable of driving 7 miles and compos mentis enough to perform the more difficult aspects of my job (as I've been called because a more junior member of staff, the one on the overnight shift, is out of their depth). I am 'covering' that staff absence for a 1/6 of my working time, as are my remaining colleagues.
The sort of pressure I'm under is also 'unique to my job'. And I could up the ante and suggest that people's very lives are at stake in mine, not a grade point at GCSE.
But still I am not advocating 'a race to the bottom', just suggesting that teachers' unions are not wise in playing the 'But we're special' card these days. So am I but the government has frozen my pay, increased my retiring age, increased my pension contributions and decreased my pension. And I get 6 weeks annual leave a year. Oh, and upped my hours by 2.5 a week for free.
PS, yes your Head can contact these people and discuss their situation. In fact, she has to! It isn't 'harassment', it's part of their 'return to work' package which, these days, can be far more proactive, legally and medically, than it used to be. This is a good thing: it 'forces' employers to not just hand-wring about a MH condition but to positively act in a way that will help the staff member who's off sick to reintegrate; and as an aside, prevents any possible malingering. I am not suggesting your colleagues are malingering, not for a second: stress is a real and horrible condition; but, there's no doubt about it, within my larger dept, 2 people (out of several over a period of time) who went off on stress leave were suddenly able to return to full capacity when, having refused to engage with the process that may well have assisted their return to health, were called in to attend Occupational Health interviews (at their own convenience) where 'alternative employment' was to be discussed. Disappointingly, both were 'older' employees, still believing that citing 'stress' lead to early retirement and a gold-plated pension.