Currently mwb's are not importable, though I know developers are fixing this right now.
This info is ALSO HELPFUL though, if you want to import a workbook in a LANGUAGE that is NOT yet SUPPORTED.
Adding midweek schedules happens in Settings - Life and Ministry Meeting - Schedule tab.
In the top box click +. You are now given a calendar. Click a Monday and select the week (you do not see the selection, but if you don't do a selection it won't work) That particular week will be added ALONG with all possible items in the bottom box.
For the following remember that adding an item to the bottom box with the + sign next to it, is not currently working. Deleting an item is working, but you cannot re-add it, so be careful.
Now in the top box, you will have to enter the Bible reading programme, and the 3 songs (double click those cells). In the bottom box, you will have to enter the title/theme of the items in the theme fields, which is best done by copying it from the workbook (online) then pasting. Then check and maybe correct the proposed timing, copy paste the source (sometimes just instructions) into the source fields.
After checking all is OK, remove the unnecessary items. (Usually Living as Christians item 3, very often also item 2). Delete by selecting the row and click the - sign. (the bottom one! If you click the - sign on the top, the whole week is gone).
You may end up with a warning about time not being as expected. A difference of 1 or 2 minutes is not exceptional.
You are almost done. There is no possibility to add lessons here. You could include them in the source material, which is a nice workaround. The alternative is to work directly in the database. If you want that, read on.
Go to the database (In settings click Open Database Location, and CLOSE TB immediately afterward), open it, and find the table lmm_schedule. Find the items you have just added by filtering on the date, which in the database always has teh YYYY-MM-DD format. Remember that... You can probably filter for the date(s) you have just added. Double click the study_number cell for each appropriate record and enter the proper lesson number. Close and save changes.
It looks daunting, but the whole thing will probably not take more than 10 mins for an entire month.
For accessing the database my personal preference is http://sqlitebrowser.org/
For editing templates I now use https://code.visualstudio.com/