Making pastry with Margarine

I make Delia's apple pie on a regular bases. If I make it with butter and lard there's little bother, but I do make the odd bloomer☹️
However, I have a friend who is lactose intolerant but when I make the apple pie for him it really is hit and miss. I use block margarine and lard on a 50/50 basis everything else is as Delia's recipe
When using block margarine instead of butter should I use a different proportion marg / lard
Many thanks

Kevin