When I send a text message on my iPhone the response comes through on my iPad iMessages only.

Messages on iPad are forwarded through an iPhone.

1. On your iPhone, iPad, or iPod touch, go to Settings > Messages > Send & Receive. On your Mac, open Messages, choose Messages > Preferences, then click iMessage. Make sure that you're signed in to iMessage with the same Apple ID on all your devices.
2. On your iPhone, go to Settings > Messages > Text Message Forwarding.*

Since you said the same iMessages is not on your iPhone there are only two possibilities

1. The messages are deleted on your iPhone. Enable  Guided Access before handing over an iPhone to kids
2. The message is forwarded from another iPhone to Mac/iPad which uses the same Apple ID but a different Phone number. Please call the person (in your case Dad) who sent you the messages and get confirmation about the phone number to which the messages are being sent.