PI Mapping query

hi

my scenario is soap to proxy.

In proxy response onerequirement is like this :

fieldname is Reference, which can come n number of times. like In response it may come-

Reference1=10,Reference2=20

OR sometimes only Reference1 will come

OR some times till Reference5 can come in response.

How this can be handled in proxy response and in ESR what i need to do for message structure like this.