I have a Data verse table named "Stage table" as shown

I have another Data verse Table named as "Loan Consignment Request Table" as shown

The stage column in the Loan consignment table is a look Up column as shown above
In the Power app form while creating a new loan consignment, I need to have the default value of stage column to be "Pending at Branch", even though the user doesn't selects any value from the stage column and submits default value pending at branch should b submitted and if he changes any value from stage column the other values should be submitted.
Please Help me out How can I achieve this my Form has stage Data card values as shown
for whole data card default value = This Item .Stage
for the particular data card item property = choices([@Loanconsignmenttables].crfe5_stage)