Hi,
You can play around with the beaming of notes to a fairly high degree.
If you have a group of 3 quavers that are beamed together, and you want to join an adjacent single quaver with those 3, the following should work for you (I just tested this here, and it did for me).
1. This example is dealing with a group of 3 beamed quavers, with a single quaver following (to the right). Click on the single quaver to select it.
2. Click the Notes and Rests/Beams palette button.
3. Now click on the "Beam left" (second) button on the Beam tool detail palette. That single quaver should now "beam left" and join the already beamed group.
You can apply the same sort of steps to join a single quaver that preceeds a group of already beamed quavers (but using the "beam right" button). The main key when regrouping the beaming patterns is to select only the notes you want to affect, which is pretty easy with click-dragging if there are more than one.
Does this answer the question? If not, please let me know.
ttfn,
Sherry