I've read several books of survivors, including Gracie's and Lightoller's books, both of whom were on lifeboat B, and none of them mentioned anything about anyone being hauled on board of another lifeboat
Neither have I. IMO, what happened was that after the
Titanic sank, Joughin swam over to the overturned Collpasible B. There were already several people standing on top of it, including Lightoller, Gracie, Bride and Maynard. It is possible that some of them were reluctant to help Joughin for fear of upsetting the already precarious 'raft'. But the chef Maynard, who probably had worked with Joughin on board the
Titanic, helped the baker to climb on board, likely with help from one or two others. There they all remained till dawn, at which time they saw a few other lifeboats and Lightoller used his whistle to attract attention of the closest one - Lifeboat#12. AB Clench, probably in charge of the other lifeboat at the time, reponded and eventually all those standing on top of Collpasible B were transferred.
Later, Joughin gave a very emblelished and highly improbable acount of his survival, claiming that he had been swimming for 2 hours before reaching Collapsible B and even then he was not allowed to board. So, he supposedly remained in the water with Maynard holding him up so that Joughin's head and shoulders were above the water level until another boat arrived. He then claimed to have swum across to the other lifeboat to be picked-up. A rather ridiculous fairy tale, interspersed with a few facts to appear authentic.