Hi David,
Try this approach.
1. Create AT view and join TAB1 and TAB2. Take TAB1.MY_ID, TAB1.MY_NUM, TAB2.MY_ATTRIBUTE, TAB2.MY_OTHER_NUM to output.
2. Create AN view with TAB1 in data foundation and join AT view in Star join on MY_ID with corresponding Temporal conditions.
3. Take MY_ID and MY_NUM from data foundation, hope you will get the desired results.
Regards,
Chandra.