Can I extend my children's visas in Thailand if their passports are set to expire soon?

Question regarding renewing my children’s visas. Their current visas expire on Oct 27, 2019 and they hold US passports. Their passports expire on May 11, 2020. Our next visa extension of stay will be for another 6 months (should expire April 26, 2020). Will my children be able to extend their visas until April 2020 or should I renew their passports before their current visas expire on Oct 27? I know entering the country requires 6 months be left on your passport but I wasn’t sure if that was the same as extension of stays. I know they will have a little over 6 months left when we would extend their current visas but I wanted to avoid any complications with processing my children’s visas. Thanks in advance for the help.