Can I attach mini keyboard to extend from 61 keys to 88?

[bingbong]

Beginner here. Sorry if my inquiry sounds ridiculous or dumb. I currently have a yamaha psr e253 and have started learning a while ago. I'd like to buy an 88 key electric piano but its too expensive for me and my parents wouldn’t spend that much. I wouldn’t be able to make that kind of money until 8-9 years from now where I can afford to buy one for myself. So what I'm thinking is to buy a yamaha pss a50 and maybe attach it on top or to the side of the e253 and change the octaves of both in order to get the whole 88 key experience. I'm really not trying for better sound or to play professionally. This is just a hobby that I have for myself and would like to play just for fun. Is my option a viable one? I really don’t have the money for a full 88 key and unless I take this shortcut, I'm stuck with 61 until I get a job long into the future. I'd love to use this shortcut if it is plausible. Should I do this?

[timothy42b]

61 keys is not much of a limitation as a beginner.  You can play all of Bach on 61 keys, I think.

Of more concern is that the keys are not weighted, and may not even be touch sensitive. 

But yes, if you really wanted to you could stack two like an organ has, and set the upper one an octave higher.  I just don't see the advantage.  If it's what you can afford, I'd continue with 61 keys, and while your technique might not improve much without weighted keys you can learn a huge amount about theory, scales, chords, accompanying, playing by ear, etc.

[quantum]

A good amount of organ music for manuals and harpsichord music can be played on 61 keys.  You will be able to play a lot of baroque music on 61 keys. 

If you wanted to get another 61 key keyboard, I'd stack them like on the organ or harpsichord.  It would allow you to play 2 manual pieces from the baroque period.  As Tim mentions, not having the weighted keys for more piano specific music can become a challenge.

Try to look around your area for acoustic pianos that people are selling for low price, or even being given away for free.