Retail sales with installations-Need inputs to configure the process

Hello Chmps,

Our client is a leading sports and Gym equipment seller for which we are implmenting the orale ebs

here the question in when the customer walks in to the store and he may pick up the porducts which he would like to carry with immidiatly while he goesout like Shoes,T-shirts, etc and also order for some gym equipments which needs the installation like treadmills.. etc..

in the above case how can we configure the Order management where a  single Sales order can be entered with both regular and also installable items

and the line should be be closed and the inventory should be reduced only when the product is sent for installation for installable items..