I presume you are talking about combining multiple orders into one package. You can mail your orders in one package if you believe your buyer is honest. Hard to find out, but check the number of FB they got as buyers. If they also sell, in the same category as you, it might indicate a potential foul play. Or they registered just recently, or have 10 or less FB. Also their messages can indicate their character.
There are scammers, (esp. in some categories like electronics etc) and they can claim that the package did not contain all orders. You can show that the package was delivered but you can't prove that everything was in.
Even if ebay sided with you (tracking shows delivered), they can dispute ebay's decision, or dispute it via PP or a credit card. Generally speaking PP and CC companies side with the buyer.
If the items are expensive, that is you cannot afford to refund the value of a potentially 'missing' item, I would mail them each separately. Of course it also depends on the weight and size of what you mail, as you don't want to pay $30-$40 for each package.
The bottom line is to consider all these factors and make a decision that you can live with, if things go the wrong way.
I routinely combine multiple orders but my category (Antique Prints), fortunately, is free of scammers.
