Wa `alaykum as-salamu wa rahmatullahi wa barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
Try to avoid serving pork to non-Muslim parents as much as you can, but you can have it for them on the table (especially if you have a non-Muslim to offer it for them instead of you).
In his response to your question, Prof. Dr. Monzer Kahf states:
This is a very important and delicate matter. Let us look at the rules:
1- Prohibition is really based on the harm involved because Allah only prohibits what is bad.
2- Things which are haram to use or eat are also haram to buy or sell.
3- In liquor, the prohibition is expanded to include all that is related to drinking from brewing to carrying, serving and drinking.
In pork, the prohibition is eating. Therefore, there are views that argue the permissibility of using pork products for non-eating purposes such as using the hide/skin for shoes.
Serving to eat is definitely different from eating but also related to it as the principle is the potential harm (which we may not know scientifically yet but we believe it by faith because of the prohibition itself).
4- There is a strong juristic argument about the lack-of-cleanliness of pork (the concept of najasah) which means that any wet thing touched by it will have impurity too and that we need to clean every tools and pots used for pork separately.
My suggestion is: it is certainly not permissible to buy any of pork products for eating even for non-Muslim guests/relatives. Also, try to avoid serving pork to non-Muslim parents as much as you can unless embarrassed by a non-Muslim father or mother (not other relatives), but you can have it for them on the table (especially if you have a non-Muslim to offer it for them instead of you).
I hope this answers your question.