My company converted to Office 365, and I now have Visio Plan I. They advise the Visio Plan II is not compatible with our limited Office 365 version.

We have 100's of older Visio files created as .vsd format. From my Visio Plan I browser, I can VIEW these files, but I cannot edit them with Visio online. I posted this question on general MS website, and MS Admin looked. There are no official converters available for me to convert the legacy .vsd files into a format I can use to edit. I don't want to use supposed converters off the web due to malware risk.

This should be standard functionality and provided to all users.