Moving from desktop pro to online - Change of admin

looking for a solution that helps me migrate data from desktop to online…. But there’s more to it!!

This seems like an easy enough problem to solve but I am having no such luck.
Here is the situation: Our current bookkeeper runs her own business and uses desktop pro to handle her clients. We want to use quickbooks online and do our bookkeeping ourselves in house. 

From what I have gathered starting from scratch does not have to be the only way to do this successfully. I have been working with the bookkeeper and she has tried to migrate data from directly from her desktop application to our online account even using the same computer but no luck after hours of loading.