Hi! I made two batches of SMBC and they came out different. The first one was perfect. The second one tastes less sweet and I dont know how to fix it. I tried adding more vanilla, but it still tastes off. I'm running out of butter and time and i was just wondering if there was another solution other than throw it away and start over. 

If it doesn't taste sweet enough, why not try added some powdered sugar?

Yep, just add in a little powdered sugar!  The texture may become a little heavier, though.  You could also try adding in some simple sugar syrup, or even making a small, extra sweet batch of SMBC to add in.

And waht about mixing the two batches together so it all has the same taste/texture?

What did you end up doing and how did it turn out?