Hi Srilatha,
Had a similar requirement recently.
What I did was that instead of changing the code of the webdynpro component as suggested above, I sorted the result in BADI enhancement.
Please use:
BADI: PT_ABS_REQ
Class: CL_PT_ARQ_REQ_EXIT
Method: TEAM_CALE_ENRICHMENT
In this method, I sorted: ch_rowlabel by rowlabel.
This sorts the entries in team calendar in Ascending order by first name.
Let me know in case you need more details.
Best Regards,
Rohit