During the era of DGSD, the Shaolin Temple and the Beggar's Union apparently had a fairly close working relationship. They were the two most powerful mainstream, orthodox sects of the DGSD period, and moreover, they collaborated in the upbringing and development of the era's greatest hero, Kiu Fung. When the Khitan, the Hsi Hsia, and Mo Yung Bok considered the obstacles facing them in conquering the Northern Sung, the presence of Shaolin and the Beggar's Union was in the forefront of their minds.
A century later, during the time of LOCH, Shaolin had receded as a wulin power, but the Beggar's Union remained strong. During this period, the Beggar's Union found itself most closely allied with the Cheun Jen Sect, which had taken over Shaolin's previous position as lead sect of orthodox wulin. During LOCH and through ROCH, one never heard about the "Shaolin/Beggar's Union" connection.
Towards the end of HSDS, there was a dispute between Shaolin and the Beggar's Union over Sing Kwun and Chan Yau Leung's treacherous acts. During an argument between Hung Tze and one of the Beggar's Union Elders, the long-standing relationship between Shaolin and the Beggar's Union was referenced. I'm surprised that anybody in wulin towards the end of HSDS would have even remembered the old Shaolin/Beggar's Union ties. Over two-hundred years had passed between DGSD and HSDS, and the Shaolin/Beggar's Union connection had lain dormant during all that time.