ATP with fixed order lead times

Hi Experts,

We have requirement where we want the Sales Order Schedule Ship Dates(SSD) for some items should be based on the Standard Delivery guide we have, irrespective of the supply availability

For Ex . Item A should always have SO SSD at 2 weeks from the Order Date. Item A might be having some onhand or other form of supplies.

But we dont want those supplies to be considered for ATP calculations and the ATP should always give the SSD at 2 weeks from the Order Date.

Note: We have ATP Check & ATP Component defined for the items as " Material Only' & The ATP results are based on the ASCP Plan o/p.