Microwave Use for Meat and Dairy foods

 Hi,I am currently living temporarily with my parents, together with my husband. My parents use a single microwave, for milky and meaty foods, however, they do have separate covers for milky and meaty (both covers are perforated). I wanted to ask how I can heat food in their microwave in a halachically permissible way, without causing them embarrassment?Thank you in advance. 

Shalom,

For non-regular use, it is permitted to heat food in a non-kosher microwave by covering it with two coverings, for example, placing the food in a container and then putting it in a plastic bag. This will ensure that the steam from the food does not come into contact with the interior of the microwave.

However, it is important to note, that this method should not be done on a regular basis, such as in your own home, since it would inevitably lead to mix ups.