Eurozone Investment accounts

[thekingisdead]

Looking for some advice and there's a few knowledgable people on here so thought I'd try before trawling google etc.

My SO is German and consequently our child has dual nationality. Long term we don't know if we'll stay in the UK or re-locate to germany or somewhere else in Europe.

Our child has a S&S JISA based in the UK. As his Maternal grandparents are based in the Eurozone he has received a small sum of Euro's (circa 3k) that I would like to invest for the long term (kept as cash it will just erode etc).

As we don't know where we (or he) will be based in the future, I'd like to keep both his Sterling investment account and open a Euro investment account.

I could exchange the Euro's but to my mind Im opening up FX risk now (albeit the £ is historically weak) and then in the future should the investment account be converted back to Euro's.

Is it possible to open an investment account with Euro's as the base currency? He has german citizenship but is not domiciled there.
Should i just keep things simple and convert the Euro's into Sterling and just accept any FX fluctuations over a 20-25yr period.

Thanks,