@kasunhp For transport related emissions, the eco-footprint module focuses on cradle-to-gate but not cradle-to-grave assessment, if my understanding is correct.

Therefore only the supplier to factory part of the life-cycle is considered for this. When adding values in the basic data (eg: Emissions per Distance and Weight Unit etc..), the values could probably be estimated standard values (eg: When ship-via is by air, the emissions are standard estimates for air cargo transportation). The application then calculates the values based on the requirement of the component parts, quantities and parameters for suppliers.

Hope this helps !

@Buddhika Kurera Thanks for your reply.
Yes. it seems impossible to estimate emissions associated with deliveries performed by a manufacturer to customers. 
I Still have a thing to be cleared, when supplier to factory emissions are calculated. Total emissions associated with an actual shipment is a result of total distance covered by the ship (if it is sea transport). There may be many parts included in that shipment. To estimate, emissions associated with one particular part, we need to know total number of parts and a breakdown of parts. Then we can do some divisions to find out proportional emissions associated with one part. Do you have any idea about this?