Thanks for your question. I will try to help.
I expect that one of the reasons that they rejected the applicatoin was because your daughter did not submit a copy of her passport. They judge the application on the evidence actually submitted with it and they regrettably won't go out of their way to estalish eligiblity from other sources (eg passport office).
SHe should really have submitted a certified copy of her passport, certified by a solicitor.
Additionally, they may consider him to be a risk of an overstay if suffcieint evidence of his compelling reasons to leave the UK after marriage were submitted. For example, he could have submitted evidence of his father's condition and a sworn statement advising them that he would return for this reason and for any other persusive ones (eg home ownership, job prospects etc)
An out of country appeal based on human rights is the only appeal which could actually be heard and out of country appeals take about 6 months to be held, so this is plainly not satisfactory for your circumstances
So, the most sensible way forward would be for your daughter and you to instruct a solicitor immedaitely based on the UK to prepare a new application. They could correct the evidential omissions and prepare a sworn statement for him to execute. The reality is that this would be the quickest way to attempt to get him a visa quickly.
I’m really sorry that the rules are so tight, but they are applied very strictly.
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