We have had most of my wife`s family to visit over the years, her Mum twice, her Dad,sister,2 brothers and I can only say there may have been an element of luck in the applications. Only once was her brother initially refused but we appealed and the visa was granted, he was 19 at the time. At the same time I sent a letter of invitation for the visit I would send a copy to the embassy with a covering letter, not sure if it was any help but the success rate was pretty good. Everything else was in place, such as good bank accounts, plenty of room for accommodation, and getting prepared for the interview.
Its been about 3 years since the last visit so not sure the procedure is the same.
The flip side is that I had a good reputation with Dee`s Aunts and cousins who live over here and they asked me to help with an application for the Aunts sister (another of Dee`s Aunts) who had been refused a visa. She made another application and I was in Manila and went with her for an appointment with someone who I thought was the Consul, but may have been the manager of the section, at the Embassy. That was when you had to get a lift up to the visa applications floor. I spoke on her behalf, explained that she had to return to the Philippines as her elderly Mother relied on her, and was assured that the visa would be granted ,no problem. Everyone was celebrating, went back to Angeles and had party and I was the bees knees.
We returned home and 2 weeks later came the news that her visa had again been refused as they thought she intended to stay. As I say it can be pure luck sometimes.
She eventually got here for her nieces wedding last year but they used a lawyer. Never been asked to help since.