Travel Kyiv to Athens?

Привіт, друзі!
Здравствуйте, друзья!
Hello Friends!
I need a little help figuring out some approximate costs for budgeting purposes.
I have two children who will be visiting Kyiv this summer to bond with their Ukrainian family. I would like to travel to Kyiv and then plan a round trip excursion with them to Athens to visit my family in Greece.
Using web tools I can easily calculate the approximate costs of round trip travel USA-Ukraine-USA. But, I’m not exactly sure how to determine a safe but economical air carrier Round Trip for one adult and two children (both age 5) traveling Kyiv-Athens-Kyiv. My dates are flexible.
If anyone in the Kiev InterNations is willing to help me figure this out, please send me a PM and let’s connect.
Thank you in advance for your consideration.
Kind Regards,
Thomas Foskaris
Ambassador – Las vegas