[TYPO3-mvc] Set relation

[Dawid Pacholczyk]

Hello List !
It`s again me. Damn hard day at work.

I`m wondering on some thing. I have mm relation beetwen object Record 
and object Portal

I have one connection Record1 <-> Portal1

Now I want to add connection beetwen Record1 <-> Portal2

How can I do that ?

First I used setPUid but I received

PHP Catchable Fatal Error: Argument 1 passed to 
Tx_Ext_Domain_Model_Record::setPUid() must be an instance of 
Tx_Extbase_Persistence_ObjectStorage, instance of 
Tx_Ext_Domain_Model_Portal given,

first of all it generates error, secondly It would replace the old 
connection. How to add another value so it would be saved in database ?

best regards,
Dawid Pacholczyk