Can I use both scripts (Madinah and South Asian) in one class?

You can use both the South Asian and the Madinah Script on the Dua books as they are exactly the same, only the font is different.

For the Complete Qaidah and Tajwid books, If your students are learning individually then in it can be done. The teacher will need to adapt to both scripts and must understand the differences between both books. There are teachers successfully using both scripts within one class without any issues Alhamdulillah. However, if you are teaching in a format where all students practice and read collectively; we recommend only using one script as the book layouts are not like for like. 

The Complete Qaidah has undergone the most change as many levels and examples are completely different; hence it will be quite difficult to teach it to a class where the students recite and learn collectively.

In the future we may look to consolidate changes across both editions insha'Allah.

You can see the visual differences of both scripts here.