births in age-class pop. model (beware the beginner!)

Greetings,
I'm a little new to DS modelling and very new to Simile ... in the learning phase.

I have downloaded an example (ageclass6) from the simultics site, to look at age-class based population models. I modified the model a little to suit my need but came up short with the results.

The youngest age-class is to contain the total number of births produced by the population at the end of an iteration. However, these are only stored in the in-flow at this stage and are only added to the youngest age class one iteration later.

It seems logical that the 'birth' value is only determined at the end of an iteration once you know what number of individuals are in the other classes. But ...the values can then not used in the 'mortality' flow during the next iteration., i.e. there seems to be a continuous lag of one iteration between the birth of organisms and the feeding into the youngest age class. This has the additional snag, that the births are not part of the total population.

Can anyone clarify this? (I'll gladly send the model)

Patrick