Custom field at Phase and Task level

Dear All,

I have a requirement where I have to add a custom field in the below components - same custom field in both these views

View VI_DET_ADD_PPO of WD component DPR_DET_DATA_PHASE_O and

View VI_DET_ADD_TTO of WD component DPR_DET_DATA_TASK_O.

Up to this its OK, now the challenge is to make the data entered in the custom field at Phase level to flow to the Task level. The idea is, all Tasks created under the same Phase should have the same value(default) in the custom field as is maintained in custom field at the Phase level.

Can anyone please give a solution for this issue.

Thanks in advance