It could be a distinct practice mode, but it's fairly easy to set up as it is. At the moment my (slightly bloated) flashcards look like this:
first 4 or 5 example sentences with underscores showing where the headwords should go (for example 堵车的话,开车__走路快__ - where the answer is 不比...多少) Then I sometimes have an English definition underneath if I think the example sentences aren't obvious enough on their own, and finally a few notes underneath about the technical points of its usage.
It means that at the moment I'm spending more time working on the definitions of the flashcards themselves than I am actually reviewing them, but I think it's going to be worth it in the long run. I found that my flashcard practice before was great for improving recognition, but the words weren't popping into my head when I actually wanted to use them in conversation. I also think that customising the cards to this extent is a good way of re-introducing 'the DIY factor' (
http://www.sinosplice.com/life/archives ... -about-srs) and combating the fact that sometimes Pleco is just a little bit TOO convenient.
As for multiple definition entries for cards, I think it would be a useful option for all the practice modes, not just 'fill in the blanks' sentences like the example I gave above.
On a different note: another useful option would be not to show how many characters you're required to input. So, for example, I might have a pair of cards with sentences testing me on the distinction between the use of 几乎 and 差点儿 - but at the moment I'd immediately know that if the answer is 2 characters long, it's 几乎, and 差点儿 if 3. But I realise that would be further adding to the options complexity at a time when you're trying to make the system easier to use.