5 tables with 3 different relation cases - Mailing list pgsql-sql

I have 5 tables related among them so that:

* T1 is parent of T2 

* T2 is parent of T3

* T3 is parent of T4

* T4 is parent of T5

However, in some cases one table is missing so that:

3 relations in total.

And yet, in some cases an additional table is missing so that:

* T1 is parent of T4,

* T4 is parent of T5

The 5 tables always have the exact same fields but, of course, the relations are different among each case.

Is there a way to design the schema so that I always have 5 tables and make T2 and T3 "invisible" for cases #1 and #2?

Or should I consider 12 tables: 5 for case #1, 4 for case #2 and 3 for case #3.

I will very much appreciate your feedback.

Respectfully,

Jorge Maldonado