Defrost and use within... Months

I work for a company who have recently started selling cream based sauces (i.e. cheese sauces, soups etc). We have adopted a model of thoroughly pasteurising in the pouch. We have proven these microbiologically with a lab for 3 month+ chilled shelf life (and some testing at ambient) and never come back with a bad result (also organoleptically tested fine). 

We have a huge freezer store but only a small chilled storage area. Before we started pasteurising (and until now) we have always stored and sold frozen.

My boss would like to label the product before freezing with a 12 month frozen shelf life with a statement along the lines of "once defrosted use within 3 months". I am trying to explain why this is not a suitable suggestion with the risk that someone defrosts it and that's such a period of time that they may forget when it was defrosted and keep it beyond that date. My boss is under the impression that this would be the customers fault for not ours but I don't think it gives clear advice, its the whole reason we apply a use by date and don't just label a tin "use within 1 year". Plus I have never seen this on anyone else's label. 

How can I persuade him that we will have to apply a use by date upon defrost, is there any legislation / guidance I can show him that will help?