mixing permanent and semi

I have recently bought 'LIVE brilliance' hair colour in Red Passion (let me know your experiences with this if you have tried it). I like the colour because it is a bright red, but still has violet undertones instread on yellow... I still wont to give the colour that little bit of something else.. i have a small amount of hot pink hair dye left over from other hair advantures.. only about enough to pour into your palm.. could i possibly mix this in with the permanent mixure to give it a pink dimention? I know it is possible to mix permanent colours together. I could always dye with the permanent then put the semi pink over the top bt because there is soo little, it will be hard to distribute evenly.. much easier to apply both dyes in one go.. long story short is it possible? or does the semi effect the developing of the permaent?