I know it's hard but I think maybe you should focus on Lola and Raven right now. When they're teething and chewing on everything, or when you have to get them spayed at the same time practically, you might even be glad you only have 2!!
Sonni is a very handsome little guy...and ultimately it IS up to you.
But you could always wait for a while and get another chi when Lola and Raven are trained, or at least a little older.
Let us know what you decide- I know it's a tough decision.
*siggy by the talented Jen*