EE family plan gifting data.

Both me and mrs have terrible signal on three, just did a speed test on sisters EE phone and got 100mbps and we both want to switch.

Im wanting to know how the gifting of data works.

I’m looking at taking out the ee unlimited sim only plan (£35) as have a discount code for 20% off. For the second line is it possible to take the cheapest option and gift 100gb per month from the unlimited plan?

Appreciate any advice.