Thank you Andrew for the custom bbcode it works like a charm, regarding the implications I will take a chance till I find some solution or till you comeup with a solution.
I don't know whether I have done right or wrong, I have tried to edit the phrase ldm_thread_create_body, but I could not edit it other than adding a translation it didn't worked even after doing that, changing sequence didn't found that option so I deleted the translation I created from the phrase table ia phpmyadmin. I have edited the original phrase phrase ldm_thread_create_body in database from
PHP Code:
A new entry has been added to {4} Description: {2} To check it out, visit [url={3}]{1}[/url]
PHP Code:
A new entry has been added to {4} Description: {2} To check it out, visit [lurl={3}]{1}[/lurl]
Now everything is working as intended and links in auto created threads are opening in same window. I hope no problems arise because of my phrase translation deletion from the database