Earbanean:

 

Has anyone used a third party app like PhotoSync to sync photos to a PC (which in turn would sync with OneDrive)?

 

We do exactly this, and photosync seems to work pretty well. Initially did make use of the auto-transfer feature, it stopped working at some point (possibly when I changed PCs) and never bothered to set it up again - noting though that we do have a family iCloud subscription which does give us extra space and therefore extra breathing room. Basically run it once a month or so on everyone's phones, more so we can delete photos and save space on the phones / iCloud ... once copied over photos then get backed up onto OneDrive and other back-ups. Of course, the only catch is, eventually OneDrive starts to get full as well!