Savings accounts for babies in Portugal

Bom dia a todos!
My family and I have moved to Portugal recently and we’re deciding on which bank to choose to open a savings account for our 8 month old son (he’s a dual citizen, British & Portuguese). The amount we’ve saved up for him so far is almost split directly down the middle with half of it being in euros and half being in pounds. Ideally we want to be able to put it all into a Portuguese account whilst retaining as many of the £s as possible when transferring them into euros. Does anyone here have any experience with a similar situation? Are there any lifetime bonds or anything worth looking into with some Portuguese banks to help him to have a little something already put away for when he comes of age?
Obrigadíssimo e bom fim de semana :blush:

P.S. Hope you’re all tuning into the euros final tomorrow :muscle: come on England!