The Requirement is for a simple Database for Deals which is open-ended and can accomodate additional attributes without redesign.
The Statement of Requirements from the User is to model the following :- 

Each structured deal has two sides of information, namely, collateral and bond, (or asset and liability).
On the collateral side, it has loan(s) level data which consists of each individual loans, and group level 
information such as group 1 total, and deal status and aggregated data such as average loan rate...etc. 

On the Bond side, there are so much derived information such as loss ratio which is simply loss ( a deal level item of information) 
divided by original collateral amount (another deal level item of information) ...etc.  
A lot of these items of information are ad hoc items and the major challenge is how to model them in the database.
 
In other words, to answer the question 'How does one deal with the problem that the Database schema grows ?'