A round knob asks a hand to grip and twist at the same time. Many fathers who will not discuss grab bars will still accept a lever on the bedroom door, because it reads as a hardware swap and not as a care plan. The job itself is small. The risk sits in which lock you are changing, because some locks keep a person in and some keep a person out. Read the lock before you pull anything.
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Name the lock function first
Take the existing handle off and look at the faceplate and the inside of the lock body before you buy anything. Most doors in a house fall into one of three types. A passage set has no lock, only a latch. A privacy set has a push button or turn on the inside and a small release hole on the outside. An entry or keyed set locks from outside with a key. Each type changes the decision.
A passage set is the easy case. Replacing it with a lever usually means matching the backset and the handing, then following the package directions. A privacy set needs more care. Keep the outside emergency release working on whatever lever you install, and test it from the hall before you close the door on it. An entry or keyed set is a different job. Do not change the cylinder, the strike, or the key lines until you have decided who will hold the spare keys afterward. That question belongs to the keys, not the hardware aisle.
Measure before you buy
Three numbers decide whether a lever fits. The backset is the distance from the edge of the door to the center of the knob hole. The door thickness decides whether the latch and spindle reach the mechanism. The handing decides which way the lever points, and that depends on which side the door swings into the room. Write all three on the same sheet as the lock label. Do not guess from a photo.
Decide: you, a handyman, or a locksmith
Do it yourself when the lock is a passage set, the old holes line up with the new lever, and the handle comes off with two screws. Hire it out when the old holes do not match, the door has been cut and filled, or the lock ties into a key system. A handyman can usually handle a passage or privacy swap in one visit and will tell you if the door needs more than hardware. A locksmith is the right call when the cylinder itself has to change or the keyed lock has to be rekeyed. Before any hired person leaves, ask what they are leaving behind: the old handle, the screws, the spare keys, and a written note of which function they installed.
Dad's side of it
He may hear a new handle as a verdict on him. Frame it as a fix for the door, not for him. Let him pick the finish or the lever shape, since that is a small decision he owns. Keep the old knob in a labeled bag in case he wants it back, and leave the emergency release and any spare key exactly as they were. If he refuses the change outright, note it and move on. That refusal is information, not a reason to argue the door.
The next move tonight
Take the existing handle off the one door you care about most, read the faceplate for the function, and measure the backset and the door thickness. Write those three numbers, the function, and the handing on a card taped inside the closet door. Then decide. Passage set, you can do it yourself. Privacy set, call a handyman and tell them to test the outside release before they leave. Keyed entry, call a locksmith and settle who holds the spares first. If you need someone who works in your area, start with Local Help in St. Louis.