The sentiment behind Prayer Chains is admirable, however...
There is no scriptural basis for Prayer Chains.
Agreement is scriptural -
However it is not by vain repetitions that God is petitioned -
The scriptural way to Pray is clearly spelled out by our Lord Jesus. -
Therefore I say unto you, What things soever ye Desire , when ye Pray , Believe that ye Receive them, and ye shall have them.
So, we are to simply Ask and Believe with the expectation that the answer will Manifest.
There is also a negative connotation to the word "chain".
A chain is only as good as its weakest link.
Is the chain strong enough?
Is the chain long enough?
No, we don`t need a chain to "move" God. We need to ask our Heavenly Father believing in His Love and Grace by which all our needs are met.
If that doesn`t seem like enough, you need a Revelation of God`s Love and Grace. It is that awareness that produces Faith with Works (results).