Well, you can always keep the SeamlyME file open while you work. When you need a new measurement, you can add it to SeamlyME, save, switch to Seamly2D, click on Sync & use the measurement.
It’s a workflow issue… not an application issue. You just need to create a measurement file (template) that contains all the measurements neccessary for the drafting system you are using. You then fill out a person’s measurements and save as a new file. You base your draft on that measurement file. You shouldn’t have to be constantly adding measurements to a file while drafting. You can store the template in a template folder. There should be several templates in the sample folder: