Did you know all the children have/had gone home?

[Tan Elaine]

Did you know all the children have / had gone home? The answer provided is 'have'. I wonder whether it should be 'had' because of 'Did you know'.

Thanks.

 

[bhaisahab]

Did you know all the children have / had gone home? The answer provided is 'have'. I wonder whether it should be 'had' because of 'Did you know'.

Thanks.

Both are possible.