Insert additional node

Hello,

I am newbie to soapui pro, however I have already made run some simple test from a Datasoursce.

Now my actual problem is more complex : I have two Table (one to many relationship) who feed soap xml request :

Table_A
id | data
-----------
1  | Adata1
2  | Adata2


Table_B
id | A_id | data
-------------------
1  | 1    | Adata1
2  | 1    | Adata1
3  | 1    | Adata1

My remote service need two parameters :
- A
- B[] array

For the first parameter, it seems simple to implement with Datasource.
But but the second one I don't have any solution : how to construct dynamicaly new XML node and insert it in the request? Please answer me if you have any solution.

Thanks