eating moldy margarine is just. . . bizarre.
anyway, we go through this with the old ILs. we explained to them over a decade ago the science around butter vs margarine, but they still buy shit-loads of margarine because "it's good for baking and makes things low fat!" and MIL bakes a lot for church events (and then, of course, eats these things), and then "it's easier to spread on bread." So, they only eat it when they eat baked goods or on breads. *face palm* which means they rarely eat butter but will "sometimes" cook with it.
Now that we do our IF thing (and we're planning on continuing for the next three months -- so when they are here -- they'll be brekkie on their own, and we'll probably get the cereal/milk and instant oatmeal and whatever bread and margarine or something (or those olive oil spreads), and then we'll do lunch/dinner with them -- primal with whatever additions they want (probably rolls/bread with margarine).
But, DS wants to do pizza twice with them: first at bowling, and then second at their place for dinner (or our place for dinner). So, we will be breaking our primal twice on holiday. And, we'll probably do a pav on christmas day.