Install Auto Forward SMS on the Android phone you need to forward SMS from.
Have SMS auto-forwarded to ANY other phone. Or if you're a developer, forward SMS to a URL or API.
More details & screenshots below.
Have incoming text messages forwarded from your Android phone to your email address and reply from GMail.
GMail allows smooth grouping of your conversations, and you can receive SMS in your GMail inbox, and reply back to the sender.
The sender will only see your mobile number, and not know you replied from GMail.
When you get an SMS on your Phone 1, have it forwarded to Phone 2, and reply remotely FROM Phone 2, back to the original sender.
The sender will only see Phone 1's number.
Simply download the PAIRING APP, pair your 2 Android phones and subscribe. The PAIRING app (app 2) has its own MESSAGES screen, plus you can export your conversations to email or save on your phone.