For some strange reason TT has added T4s for both of my children to one child's return. When I try to manually delete the erroneous T4s, it will not let me.

Clear your browser cache with instructions here https://turbotax.community.intuit.ca/replies/2647843

You may also want to try a different browser as well, this may help the process.

Start a new return and ensure all Tslips are associated with the correct name.