>Have you tried using shortening in those recipes instead of margarine?

Unfortunately, I have to avoid soy (in Crisco) and corn (citric acid
in Lard) between my kids, too.
I tried Spectrum Spread, but my daughter may have reacted to it (may
have just been too much sugar in the cake, too.....I'll have to do
some more tests with her to see if that Spread is OK.

Do you substitute Shortening 1:1 for Margarine called for in the recipe?