All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
If your two children cannot walk, then there is nothing wrong with you performing tawaf while carrying them. You can also put them in a stroller and perform tawaf and sa‘y while pulling them. Tawaf in this case will be valid on your behalf and on behalf of your two children as well, according to the preponderant of the two scholarly opinions.
Allaah Knows best.