Thank you very much for your answer!There is no law in the Qing code which states bannerman can't marry outside of the banners, including Han civilians, but its a historical tradition that they do not marry people from the outside. Only Qing royalties occasionally marry Mongols because of political alliances, but not the Zunghars. However, Qing royalties also married with Wu Sangui's family, so its the same with the Han. There are almost no instance of Manchus marrying Uighurs outside of Rong fei (fragrant concubine), but that's an exception to the norm. There is really no standard marriage ideologies for the Manchus, they married outside of the banners for political reasons.
I wanted to ask you what you think about the claims of this paper "Interethnic marriage in Northeast China, 1866–1913 Bijia Chen Cameron Campbell Hao Dong":
"The policies that governed marriages between bannermen and civilians changed over time. Right after the Qing was established, intermarriage between Manchu and Demographic Research: Volume 38, Article 34 Demographic Research 937 Han was encouraged in order to reduce tensions between the two groups. However, the policy did not work well and the Qing court quietly canceled the policy soon afterwards (Rawski 1991: 181–182). Subsequently, intermarriage between bannermen and civilians was prohibited during the early Qing, mainly to prevent Manchu women from marrying Han men. Starting during the reign of Kangxi (1661–1722), men in the Eight Banners were allowed to marry Han women under specific conditions. This practice became common during the Qianlong period (1736–1795). The prohibition against intermarriage between the banners and Han was revived in the Jiaqing period (1796– 1820) and then relaxed again in 1865. The rule that forbade daughters of bannermen from marrying Han civilian males was amended so that it applied only in Beijing (Ding 1999: 343–344)."
Thanks in advance.