A soft-enter (shift+enter) certainly works for splitting a regular calculation rule onto multiple lines. Have you made paragraph markings visible in MSWord so you can confirm the shift+enter did indeed register as a soft enter?
See section 7.2.5. Soft Enters in Calculation Rules for what it looks like with regular calculation rules: http://www.oracle.com/technetwork/apps-tech/policy-automation/learnmore/policymodelingbestpracticeguide-1371173.pdf
You can also you the ForScope or the English equivalent of any For operation "In the case of"
In the non-function form:
In the case of relation01
In the case of relation02
in the case of relation03
In this each function is at a new rule level. The advantage of this approach is you can have multiple rules and each level as you normally would. In the normal functional For operation you must resolve everything in a single attribute.
You should always try to avoid over-nesting things by trying to create intermediate attributes. The simplest reason for doing this is that it makes debugging that much easier - you can see what the value is rather than trying to work out what it is being combined together as.
Sometimes that is not possible when performing certain complex cross entity reasoning - but given that you were using the For operator that is unlikely to be the case here.
Also given you were using the For operator I'll raise the question of whether or not any of the relationships you are traversing are containment relationships? Because if they are all containment relationships then you don't need to use the for operator at all. If any are containment relationships then you can exclude those layers which are traversing the (reverse) containment relationship.