Parent/Child Listing Variations - Whats the most efficient way?

I am stuck! I have tried following all guidelines and still I am struggling to add new variants into my product (although I already have a parent and 3 child listings I am unsure how to add in new colours).

Can I copy child listings for each individual colour and then attach them at the end to the parent?
Seems extremely time consuming so thought there would be a quicker way?

Many thanks,

Bianca