twins then triplets!

So my best friend found out she was pregnant from a 1 time whoopsie.. she goes to her first ultrasound and finds out she is having twins! Now she already has a 6 year old, so she panicked for a few days then came to terms with it. She has had like 2 scans since then because she is a high risk pregnancy due to incompetent cervix. Anyway..Yesterday she went to the dr for a 20 week scan and finds out it's actually not twins.. it's triplet baby boys!!