In Alien Isolation it worked really well because it felt like a piece of the plot that worked and served to expand the universe and the canon. It wasn't too far fetched because it was entirely acceptable that her daughter would go searching and in that respect, encounter/be included in this nightmarish timeline of events.
In Covenent however, I fail to see how, by adding Her mother, it adds any structural significance to the plot. For a Ripley to be intertwined in this story it just seems too tacked on for the sake of the moniker. It just doesnt make sense at the moment. Saying that, it is early days yet and i guess if they do go down this route then all will become clear...will there be a convincing reason for her inclusion though? That is the biggy.