How do you calculate ABV when you add additional fermentables during secondary fermentation?

I just made a 1.050 wheat beer that finished at 1.008 or 5.5% ABV. Then I added 3# (5 cups) of Vintner’s Harvest Peach Puree (SG 1.043) as a secondary. The finished beer is again at 1.008? I guess because there are more solids along with the additional alcohol, the net change in apparent attenuation is zero? Does this sound correct? So what is the ABV of this beer?