Doing a Google search with "convert ofm to dst" pulled up a load of hits.
I read more of the links and found that even though I don't do embroidery, it may be as easy as finding one of the users here with OFM to open it and just save it out as DST.
Per Embroidery.com....
How do I convert embroidery formats?
If you have an embroidery design that your machine cannot read because the format is incorrect, you can convert it to another embroidery format -- one that your machine can use. To do this, you need embroidery software on your computer.
To convert embroidery formats:
Open your embroidery design.
Make any changes needed.
Click the disk icon or from the file menu and choose "save as".
This opens the saving window so you can choose your saving location (which folder or drive to save to).
Change the file name if you wish to.
At the bottom is a dropdown list of formats.
Select the format you would like to convert to.
Click save.
