I have a problem with an Anacrusis

I am working on a "Theme and Variations" piece and several of the variations start with an anacrusis.

Having entered the Theme I can then start a new section by placing a section break at the relevant point, but I then cannot set up the anacrusis at the start of the next section. (Incidentally it also involves a change of time signature from 4/4 to 12/8).

I *can* do it by inserting rests and making them invisible. I can then improve the visual aspect of the score by selecting the rests and using the inspector to change the 'horizontal offset' and 'leading/trailing' space so that they take up less space. However that doesn't completely reduce the space or solve the underlying issue and is rather a messy way to do things!. In any case if the variation involves a repeat (in my case they don't - but in other cases they might!), then it is necessary to fiddle about with first and second time bars and putting a 'Start repeat' at the first full bar after the anacrusis in order for the score to play back correctly.

Is there a way of setting up an anacrusis correctly in this situation or do I have to continue with this workaround?

Many thanks
Andrew