Prepare Target source data for Sankey diagram

Hi YeltsinC ，

You can follow the below steps to get it, please find the details in the attachment.

1. Create a calculated column to get the target SNKID

Target = 
CALCULATE (
    MIN ( 'Table'[SNKID] ),
    FILTER (
        'Table',
        'Table'[ID] = EARLIER ( 'Table'[ID] )
            && 'Table'[YEAR] > EARLIER ( 'Table'[YEAR] )
    )
)

2. Create a measure to get the sum of Value

NValue = 
CALCULATE (
    SUM ( 'Table'[Value] ),
    FILTER ( 'Table', NOT ( ISBLANK ( 'Table'[Target] ) ) )
)

3. Create a Sankey chart (Source: SNKID   Destination: Target   Weight: NValue)

Best Regards