Measure

Hi HARSUE , you are very close.

USERELATIONSHIP activates an inactive relationship, but it does not deactivate any active relationships.

So, if you currently have an active relationship between Date and FCT_Orders (by OrderDate) and you use USERELATIONSHIP to also relate Date to FCT_Offertes[StartDatum], then:

Date will filter both FCT_Orders by OrderDate and FCT_Offertes by StartDatum.
Through the active OfferteNr relationship, FCT_Offertes then filters FCT_Orders as well.

Assuming your active relationship is between 'Date'[Date] and FCT_Orders[OrderDate] (replace OrderDate with your actual date column), you can explicitly disable that relationship inside the measure:

Orderbedrag uit offertes :=
CALCULATE(
SUM ( FCT_Orders[Bedrag_Excl_BTW] ),
FCT_Orders[OfferteNr] <> BLANK(),
FCT_Orders[Artikelgroep] > 99,
-- Use the Date -> Offertes relationship for the quotation date
USERELATIONSHIP ( 'Date'[Date], FCT_Offertes[StartDatum] ),
-- Disable the Date -> Orders relationship for this calculation
CROSSFILTER ( 'Date'[Date], FCT_Orders[OrderDate], NONE )
)

If your table visual is already built on FCT_Offertes (and the Date table is related to FCT_Offertes[StartDatum]), you can also drive the filter from the quotations directly, using VALUES and TREATAS.
Example:

Orderbedrag uit offertes :=
VAR QuotesInContext =
VALUES ( FCT_Offertes[OfferteNr] )
RETURN
CALCULATE(
SUM ( FCT_Orders[Bedrag_Excl_BTW] ),
FCT_Orders[OfferteNr] <> BLANK(),
FCT_Orders[Artikelgroep] > 99,
-- Keep only orders that belong to the quotations in the current context
TREATAS ( QuotesInContext, FCT_Orders[OfferteNr] )
)
 

If this response was helpful in any way, I’d gladly accept a ‌‌much like the joy of seeing a DAX measure work first time without needing another FILTER.

Please mark it as the correct solution. It helps other community members find their way faster (and saves them from another endless loop ‌‌.