Is it possible for multiple android applications to access a single firebase backend. If no what is the alternative in such situation?
Yes, it is! a single firebase database can be access by multiple app.. provided each of your apps use the same authentication details. The Firebase documentation will be a big help. https://firebase.google.com/docs/ I have 2 of my app accessing 1 firebase database account, so, i am quite sure it will work for you my friend!