Hi all. I have a question regarding BE on international and domestic flights (2 separate itineraries). Hope it's ok to ask here rather than start a new thread.

I jumped on a cheap direct flight to EWR in Basic Economy. Flight is with United, but flight numbers are SN/LH.

I then separately bought a domestic itinerary in United Basic Economy, which means only a small personal item.

Are they generally pretty harsh on the size of 'personal items' on a domestic flight? I'm just intending to carry a backpack (that's still certainly too big). Could I use the excuse that I'm coming off an international flight (with a bigger allowance) or will that not fly due to the separate itineraries?

Thanks!