Generate New table or calculated columns based on column and rows

lyndaGough,

This solution uses both calculated columns and a calculated table.

1. Create calculated column [Start Date]:

Start Date = 
VAR vPerID = 'tbl_007SaferMeCIN – Form Details'[PER ID]
VAR vMeetingDate = 'tbl_007SaferMeCIN – Form Details'[CALC_001 Date of Meeting]
VAR vFirstMeetingDateOutcomeYes =
    CALCULATE (
        MIN ( 'tbl_007SaferMeCIN – Form Details'[CALC_001 Date of Meeting] ),
        ALLEXCEPT (
            'tbl_007SaferMeCIN – Form Details',
            'tbl_007SaferMeCIN – Form Details'[PER ID]
        ),
        'tbl_007SaferMeCIN – Form Details'[CALC_002 Safer Me CIN] = "Yes"
    )
VAR vPrevMeetingDate =
    CALCULATE (
        MAX ( 'tbl_007SaferMeCIN – Form Details'[CALC_001 Date of Meeting] ),
        ALLEXCEPT (
            'tbl_007SaferMeCIN – Form Details',
            'tbl_007SaferMeCIN – Form Details'[PER ID]
        ),
        'tbl_007SaferMeCIN – Form Details'[CALC_001 Date of Meeting] < vMeetingDate
    )
VAR vPrevMeetingDateOutcome =
    CALCULATE (
        MAX ( 'tbl_007SaferMeCIN – Form Details'[CALC_002 Safer Me CIN] ),
        ALLEXCEPT (
            'tbl_007SaferMeCIN – Form Details',
            'tbl_007SaferMeCIN – Form Details'[PER ID]
        ),
        'tbl_007SaferMeCIN – Form Details'[CALC_001 Date of Meeting] = vPrevMeetingDate
    )
VAR vCountOutcomeNo =
    COUNTROWS (
        FILTER (
            'tbl_007SaferMeCIN – Form Details',
            'tbl_007SaferMeCIN – Form Details'[PER ID] = vPerID
                && 'tbl_007SaferMeCIN – Form Details'[CALC_002 Safer Me CIN] = "No"
                && 'tbl_007SaferMeCIN – Form Details'[CALC_001 Date of Meeting] > vFirstMeetingDateOutcomeYes
                && 'tbl_007SaferMeCIN – Form Details'[CALC_001 Date of Meeting] < vMeetingDate
        )
    )
VAR vResult =
    SWITCH (
        TRUE (),
        'tbl_007SaferMeCIN – Form Details'[CALC_002 Safer Me CIN] = "No", BLANK (),
        ISBLANK ( vCountOutcomeNo ), vFirstMeetingDateOutcomeYes,
        vPrevMeetingDateOutcome = "No", vMeetingDate
    )
RETURN
    vResult

2. Create calculated column [End Date]:

End Date = 
VAR vMeetingDate = 'tbl_007SaferMeCIN – Form Details'[CALC_001 Date of Meeting]
VAR vNextMeetingDateOutcomeNo =
    CALCULATE (
        MIN ( 'tbl_007SaferMeCIN – Form Details'[CALC_001 Date of Meeting] ),
        ALLEXCEPT (
            'tbl_007SaferMeCIN – Form Details',
            'tbl_007SaferMeCIN – Form Details'[PER ID]
        ),
        'tbl_007SaferMeCIN – Form Details'[CALC_002 Safer Me CIN] = "No",
        'tbl_007SaferMeCIN – Form Details'[CALC_001 Date of Meeting] > vMeetingDate
    )
VAR vResult =
    SWITCH (
        TRUE (),
        'tbl_007SaferMeCIN – Form Details'[CALC_002 Safer Me CIN] = "No"
            || ISBLANK ( vNextMeetingDateOutcomeNo ), BLANK (),
        'tbl_007SaferMeCIN – Form Details'[CALC_002 Safer Me CIN] = "Yes", vNextMeetingDateOutcomeNo - 1
    )
RETURN
   vResult

3. Create calculated table:

New Table = 
CALCULATETABLE (
    SUMMARIZE (
        'tbl_007SaferMeCIN – Form Details',
        'tbl_007SaferMeCIN – Form Details'[PER ID],
        'tbl_007SaferMeCIN – Form Details'[Start Date],
        'tbl_007SaferMeCIN – Form Details'[End Date]
    ),
    NOT ( ISBLANK ( 'tbl_007SaferMeCIN – Form Details'[Start Date] ) )
)