Link account balance to an entry in another account?

[AC]

Is it possible to have a link between the balance of an account and an
entry or starting balance of another one such that the entry is always
up to date?

For example, suppose I have a checking account with balance X.  I create
a new account Foo whose very first transaction is the checking account
balance (so X).  If I add a new record to the checking account that
changes the balance to Y, the entry in Foo should change to Y.

The idea here is a scratchpad for testing out transaction scheduling
(meaning schedule in real life not the schedule in Gnucash) and the
ultimate balance.