Hi ,
Where to find those related table of a table?
Is it in Maintain Table Definition but where?

Normally I have to go to SQL Queries > Maintain Query Data > Insert a table.
Then highlight the table>Specific>Add related table.
But this is a troublesome method of obtaining related table.

Anyone can help?

Use Print Table Definition ?
This gives the Reference Table information for the fields of a table.

Hope this is what u r looking for.

There is also this, to find the Child references for a given parent. These are old instructions I have for Unix only:

in $BSE/application/dd<package combination>/d<package>/<module> view file d<package><table> and look for lines starting with ':REFC'.

Example: file dtdpur041:

Column 1234
:REFC:tdpur045.cmbe 0 r1
:REFC:tdpur047.cmba 0 r1
etc.

Column 1: Reference Mode where
0 = Mandatory
1 = mandatory unless empty
2 = not mandatory

Column 2: Update Mode where
c = cascade
n = nullfiles
t = restricted lookup
r = restricted with counter
'' = no check

Column 3: Delete Mode (same as Update)

Column 4: Check by DBMS where
0 = no
1 = yes

thanks to everybody