The Wisconsin Senate was split 17 Republicans to 16 Democrats before Galloway resigned. Her resignation made it 16-16.
With Petrowski replacing Galloway (a Republican for a Republican) and Lehman replacing Wanggaard (a Democrat for a Republican) the Senate will be split 17 Democrats to 16 Republicans.
It is moot, however, since the Senate is out of session until next year and the November elections should result in the Republicans picking up at least a couple of Democrat seats.
I'm not sure what your point is.