Butter quantity missing in biscuit receipe - please could you tell me how much?

[Purpleroxy]

So I promised dd we would make these biscuits - receipe from Disney activity book! But the quantity of butter is missing and I was hoping anyone good at baking could guess at a suitable amount? And whether sunflower margarine or butter would be best as the list states sunflower margarine with no quantity but the method states butter and doesn't mention the marg - also no quantity? Thanks for any help.

The other ingredients are listed below:
215g plain flour
1tsp baking powder
Pinch salt
"Sunflower margarine" or butter?
115g soft light brown sugar
1tsp ground cinnamon
1 egg yolk
200g icing sugar
1tbsp lemon juice
1tbsp water
Edible silver balls

Bump...any bakers around?

without looking up any of my biscuit recipes, I would just for about 150g and see how you get on

Thanks so much - my 6yo v pleased we are going to make these!