I recently discovered and subsequently devoured "Multi Tongue Kids". Their setup is very similar to ours, only with different languages. I very much liked the "Family Language Diagram" on the blog, so I did one for us as well.
I intend to update this regularly because part of the magic is that it changes all the time!
I will also try to make a couple of those depicting the past (when BK1 started to speak, before BK2 was around, after 4 weeks in Algiers, and so on). Should look good as a movie :-)
One thing to note in this first diagram is the absence of English. While we all speak English, we do not use it in house. My guess is that it'll creep into the picture now that BK1 is in school.
The other interesting aspect: Souad speaks two languages. I have always thought of it as one ("that funny mix they speak in the Maghreb countries"), but BK1 is clearly not agreeing. Since we spent a lot of time in France this summer, she has become so much better and she now doesn't mix French and Arabic anymore.
[Update] Souad rightly points out that although Ines uses words from all three languages, she doesn't really "speak any of those languages" yet. So I changed the diagram.