Displaying a Row as Fixed, when it's value needs to be manipilated

[Yrstruly2021]

*I have trouble converting the data type of Column Amount in Source ABC to Decial/Numbers for this tutorial(help needed),

see data source:https://drive.google.com/file/d/1VZJv8sPPYPcLiRKyO1fkEqbcsX-dz10P/view?usp=sharing .  PBIX:https://drive.google.com/file/d/1wfjbLI7nBLQU5-Qs5rGHOL2XP4uc0UR9/view?usp=sharing 

I am trying to include rows in a Dax calculation from a mapping table(Pivot) to a fact table(ABC). The DAX is going to look at specific rows and bring those forward. The big issue is some rows are not present in the Fact table. I also need those rows to be displayed but their values to be manipulated.

An example is row "Interco capital returned", which is not in the Fact Table(ABC), it should display a fixed value of "678"

TotalAmountForSelectedItems5 = 
CALCULATE(
    SUM('ABC'[Amount]),  // Corrected Column Reference
    'ABC'[Roll_Up_Function] IN {
        "Cash flow from ops - management",
        "Cash flow from trading",
        
        "Depreciation and amortisation",
        "IPEP expense",
        "Disposals & impairment of fixed assets",
        "Profit on disposal of pooling equipment",
        "Scrapped pooling equipment",
        "Impairment or valuation adjustment of pooling equipment",
        "Disposals or valuation adjustments of other fixed assets",
        "Other cash flow from trading adjustments",
        "Share-based payments expense",
        "Working capital mvts incl. provisions",
        "Working capital mvts excl. provisions",
        "Debtor movements",
        "Creditor movements",
        "Inventory movements",
        "Prepayment movements",
        "Provision movements",
        "Change in capex creditors",
        "Change in loss compensation balances",
        
        "Interco interest and guarantee fees",
        "Interco cash flows",
        "Interco royalties",
        "Statutory reallocations",
        "Internal restructuring",
        "Interco dividends Total",
        "Change in interco balances",
        "Change in interco recharge clearing",
        "FX on interco debt",
        "Interco capital returned"
    }
)

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