That’s what I see locally. My silly sister-in-law had Covid early on before any jabs. After that, she took all of the jabs. She has had Covid two or three times since taking the jabs. Why?
Assuming the diagnosis was correct for your SIL’s initial ceebug event the short answer to later events is that the triple shot jabs knocked out at least 15% of the immunity she might have gained from the initial bug. There are lots of examples of this exact circumstance. The next question should be whether the subsequent events are really covid or are reactions to the shots. Remember that testing positive with a nasal swab doesn’t actually confirm covid——it just means one has a dirty nose.