my phone and computer are mixing up my mom and sisters contacts. whenever i text my sister it sends it to her and my mom or vice versa. whenever i get a tex from my sister it says that i have gotten a text from my mom on the notifications. How do i fix it

This is happening to me too with the iPhone 6.

I was getting text messages that appeared under the wrong contact names...I would respond to them and the person had no idea what I was talking about (because they were really sent from another contact!!)

I restarted my phone several times and it did not fix the problem. I deleted and re-added the contacts involved. I don't want to delete all my text messages (I need them) but this is potentially a very embarrassing problem!

Can anyone help?

Well that depends

Are these going out as iMessages, Blue?

Or

Are they going out as SMS or MMS, Green?

If they are Blue, it could be

Sent to the wrong Number or Apple ID

Send a message to the Number and or Apple ID, type in the full number or ID and send it.

They might be signed in with one anothers Apple ID and or number

Verify they are just getting messages for their Apple ID and or number

( on their iPhone check, Setting > Messages > Send and Receive)

If the message goes as Green

SMS and MMS are carrier related, and are just sent by phone number

Send a message to the Number by type in the full number in and send it.

Either way you can have them text and and use that new thread for them.

BEST OF LUCK

Maybe the circuit components have mistakenly automatic electricity.

That would have been virtually impossible. Maybe the devices were switched without removing Activation Lock.