Jira cloud Automation Add numeric field values of multiple tasks to one field linked via "Parent of"

[Adam LaCoste]

Hi All, 

I am attempting to combine several different custom field values from several different sources into one field of a linked issue and hope someone can help me.

Source Task 1 Custom fields (Child of) = 25

Source Task 2 Custom fields (Child of) = 139.5

Source Task 3 Custom fields (Child of) = 40

etc.

Update Task Custom field (Parent of) = sum of Task Source Custom fields (Child of)