Li Linfu and Li Shimin were relatives, and the specific relationship was that Li Linfu was Li Shimin's younger brother.

According to the search results, it was impossible to determine if Li Linfu was a descendant of Li Chengqian. The search results did not mention the family relationship between Li Linfu and Li Chengqian. Therefore, it was impossible to draw an accurate conclusion.
Li Chengqian was the eldest son of Emperor Taizong of the Tang Dynasty, Li Shimin. He was appointed as the crown prince and was highly anticipated and nurtured. Li Shimin had conflicting trust in Li Chengqian. As a father, he loved and trusted Li Chengqian very much, but as a monarch and minister, he was worried that he might do something disloyal. However, the specific information about the interaction and relationship between Li Chengqian and Li Shimin was not clear.
The relationship between Li Shimin and Li Longji was that of grandfather and grandson. Li Shimin was Li Longji's great-grandfather. Li Shimin was the father of Li Zhi, Emperor Gaozong of Tang Dynasty, and Li Zhi was the father of Li Longji. Therefore, Li Shimin was Li Longji's grandfather, and Li Longji was Li Shimin's grandson. The relationship between them was of great significance in the Tang Dynasty's inheritance and family glory.
Li Chengqian was the eldest son of Li Shimin, Emperor Taizong of the Tang Dynasty. Li Shimin ascended the throne after the incident at Xuanwu Gate and appointed Li Chengqian as the Crown Prince. He hoped that Li Chengqian would become a good Emperor and ensure the stability of the Li family. Li Shimin had poured a lot of effort and resources into cultivating Li Chengqian, and he attached great importance to his education. However, Li Chengqian's fate was far from satisfactory. He was deposed as Crown Prince and executed, probably because of his plot against Hou Junji. Li Chengqian's destiny was full of trickery and tragedy.
Li He's ancestor, Li Liang, was the uncle of Li Yuan, the Tang Gaozu. Li Shimin was Li Yuan's son, so Li He was a descendant of Li Tang's imperial clan. He and Li Shimin were of the same clan, but they lived in different eras. Li He's family had declined by his generation. While waiting for the TV series, he could also read the exciting content related to this site!
Li Linfu was Li Chengqian's descendant. Li Chengqian was the crown prince of Emperor Taizong of the Tang Dynasty, while Li Linfu was the great-grandson of Li Shuliang, the prime minister of the imperial clan of the Tang Dynasty. Thus, Li Linfu was Li Chengqian's descendant. As for why Li Linfu opposed Li Xiang, the search results did not provide any relevant information and could not answer.
Li Linfu had six daughters. Five of the daughters chose their own marriages through the "Selection Window" set up by Li Linfu and married young talents from official families. These five sons-in-law were all young men of noble birth and talent. They held official positions in the court and had limitless prospects. They were respectively married to Zhang Boji, a Honglu Shaoqing, Zheng Ping, a member of the Ministry of Revenue, Du Wei, a remonstrant doctor, Yang Qixuan, and Cao Yuan, a household of the Jingzhao Prefecture. However, Li Linfu's other daughter, Li Tengkong, did not choose to marry. Instead, she devoted herself to the Dao and became a monk on Mount Lu to cultivate. She was the only daughter of Li Linfu who had left her name, and she was praised by the great poet Li Bai for her noble character and advocating Daoism. As for Li Linfu's other daughters, the search results did not mention anything about them.
Li Chengyin and Li Shimin were not directly related. Li Chengyin was the fifth son of Li Ze, Emperor of the Feng Dynasty, while Li Shimin was the second son of Li Yuan, Emperor Taizong of the Tang Dynasty. There was no direct relationship between father and son or brother. Therefore, the relationship between Li Chengyin and Li Shimin could not be determined.
Li Maozhen and Li Shimin were not directly related. Li Maozhen was a warlord from the end of the Tang Dynasty to the Five Dynasties, while Li Shimin was Emperor Taizong of the Tang Dynasty. The time and place of the two were different, and there was no clear relationship between them. Therefore, Li Maozhen and Li Shimin were not related.
The relationship between Li Longji and Li Shimin was that of a great-grandfather and great-grandson. Li Shimin was the great-grandfather of Emperor Xuanzong of the Tang Dynasty. Li Shimin was the son of Li Zhi, Emperor Gaozong of Tang Dynasty, and Li Zhi was the grandfather of Emperor Xuanzong of Tang Dynasty. Therefore, Li Shimin was Tang Xuanzong's great-grandfather, and Tang Xuanzong was Li Shimin's great-grandson.