Im afraid you can’t add people to publications on the mobile app only on the desktop version.
As a mother of an 18 month daughter who has to sacrifice time with me for work during the week I make it a rule to not pick my laptop up during the weekend. That is our time and I cling onto it with all I have.
I will be starting back at work tonight after she has gone to bed, completely understand if you don’t want to wait to publish and go elsewhere. Either way I will add you tonight so you have an option to publish in future.