My daughter was this way. I agree that the only thing that fixes it is age. :-(
I wore a 'backpack' style carrier that had her on my front, facing out. She wanted to "see" and "be involved"!!!
She was attached to me until she outgrew that carrier - around 11 months. But the bonus is - both my hands were free so I could get stuff done.
Also - I answered your other post BEFORE I saw this one. The two are related. Your older daughter ABSOLUTELY is being affected by your other daughter. No worries - perfectly normal. But all the more reason to back off the potty training and let her own the process and do it all herself when she's ready and on her terms. If you force it, she'll get resentful and it will take longer and be more frustrating for the both of you. With 2 kids under 3 your goal should be to try and get the desired result but the EASIER way for everyone involved.
Another thing to ponder. My high needs baby who wanted me constantly so I had to 'wear her' or she screamed...... well, she'll almost 11 now and wants to constantly come home and go into her room and read the Twighlight Series books and text her friends while doing her homework and pondering how great it will be when she has her own apartment and her cool bigmoney job!!!!! When she does emerge from her room she is attached to her ipod. - not really all the time.... but it seems like it!!! lol.
So know that your high needs baby and daughter who won't go in the potty will be 10 and 13 in the blink of an eye and their world will revolve around their friends and NOT YOU. I know, I know, you hear it all the time. But it's true!!!!!
Enjoy this time. It passes quickly and even though it's frustrating.... how you handle it now sets the stage for how you handle the stuff that comes at 4, and 6 and 8 and 10 and 15 and 17. Because they are all dramatically different stages that are EXACTLY THE SAME :-)