Hello fellow cleaners

, I just joined your community to talk the business of cleaning. I guess I'll let you know a little about me, where I am, and what my question is.
First, I'm a 31 years old, and my wife (won't give her age, lol) and I currently clean private homes and an office or two. We've been cleaning together for our entire married lives, close to 9 years now. I had cleaned for apartment communities, pressure washed parking lots and fast food restaurants, and washed windows prior to meeting my wife. I've done a lot of things, but that is what relates to cleaning. My wife had cleaned a couple private homes with another lady. After marrying, we sub-contracted, cleaning banks and car dealerships locally, until the person we worked for lost the contracts due to being underbid.
The first several years of marriage, we worked almost exclusively for apartment communities, cleaning vacant units, common areas, and office areas. We were growing, and hired my dad and brother to work with us, dad full-time and my brother part-time. Things were going great, and then, like always, there was a shakeup in the local apartment management. Managers were always moving from place to place, and if the new manager that came in had a cleaner they worked with in the past, you were gone. This particular time, however, a lot of our work was with one huge property management company. They sold off all properties, and we lost 60% or more of our business in one day. I never intended to put all of my eggs in one basket, but they had a lot of eggs, and a lot of money, until they sold out.
The next several years, until now, we moved into cleaning primarily for private homes. We offer weekly, bi-weekly, and monthly service. Additionally, I have a mobile auto detailing business that I work very much part-time on the side. Our customers love us. Things are fine, but we want to learn how to expand and grow this business. We don't want to do all of the work forever, and cleaning 2-3 homes in a day is tiring by ourselves. In the past, we've tried to hire a person or two to work with us in hopes of turning over some accounts to them. However, we find that our current customers aren't trusting of the newbies. They like my wife and I, and want us to work there. Also, in our area, it can be difficult to price homes higher than what would amount to $20-25 per man (or woman) hour worked. That doesn't always leave much of a margin, though it's fine for my wife and I.
So, does anyone have any advice on growing this house cleaning business? The truth is that I don't even advertise much, but if I did, I could get a ton of houses to clean. However, I don't necessarily trust others to do the job that I would do. I would have to start the newbies at the new houses so as to avert the prejudice against them when my wife and I work on a house for a while together. How easy is it to find people that are willing to work part-time, and at times unsteady hours?
Getting the business isn't a problem, developing it with other people is. How did you grow your business? Right now I own my own job, but I'd love to turn it into something more.
Thanks to anyone that reads all of this, lol.