No worries, can even mix different grades/spec within reason, but bear in mind then the whole lot of oil will then be at the lower spec/grade.
There is an old saying that goes, any oil is better than no oil, and it is spot on.
I know what i have where now , But next top up maybe not ! knowing me . i did not have enough of the same brand to fill the transfer box , So ive had to use another brand .
But if same spec can be mixed that's great