Can someone else drop, place or replace my ball for me?

Normally only the player may drop a ball, and a player must authorise someone each time before they lift it. Rule 25 changes this:

• Players who are blind, amputees, and players who use assistive mobility devices may give a general authorisation to any other person to drop, place and replace their ball, without limit, for the whole round.
• Lifting on the putting green: for players who are blind, use mobility devices or have an intellectual disability, the player's aide, as well as their caddie, may lift the ball on the green without being asked.
• Amputees and mobility device users may replace a ball by hand or with another piece of equipment, such as rolling it into place with a club.

Dropping from knee height: because some players can't tell whether they've dropped from knee height, the Committee should accept the player's reasonable judgement and all reasonable efforts to drop from knee height, given their physical limitations.

Source: Rules of Golf (2023), Rules 25.2g, 25.2h, 25.3c, 25.3d, 25.4a, 25.4e, 25.5d and 25.6b.