First base, one of the top 4 positions defensively on the field yet neglected by coaches on many teams. First base shouldn't be stereotyped as the position for the tall lanky girl on the team or the larger girl that makes a big target. It should assigned to the girl skilled at catching the ball regardless how it is delivered her way. Having a team of all star fielders is worthless if your first base person can't catch.
One of the many obstacles you may need to overcome as mentioned by Bink44 is the girls being instructed to "Always use 2 hands" to catch the ball. I've warned coaches for years to be very careful how you instruct a girl how to do something because most are going to do exactly what you tell them without exception. Example; a runner on first is instructed by her coach to not get picked off. She will respond by not taking a lead. Can't pick her off if she never leaves the bag but look what happens to your chances to advance her. Catching with 2 hands instruction needs to be handled with kitten gloves, pun intended, and include the one-handed stretch to get everything and anything hit their way. After all, we want an attempt at everything don't we?
The idea that a stretch is needed to play first base is overrated. Let me explain why. During practices I would make a game out of it by making girls stretch for balls, even diving for balls. They would get rewarded for stopping everything or anything they could. Again, good first base players can and will stop anything to save the advancing of runners during the game. Again, careful instruction here. I want my first base person to come off the bag for those balls they won't be able to get any other way. This is just as important as a stretch. My goal is to help them see they can field one-handed and more importantly know we want an effort at all costs. The stretch comes natural when they make an attempt.
What we really want is balance.A good first base person needs to be on the balls of her feet first and mobile to react to each situation. If a ball is coming to her from a teammate, she needs quick feet to establish her presence at the bag to receive the throw. Once there, she is going to react to the throw wherever it is headed. She cannot do this if you put her in a position to stretch herself to the ball. Once she stretches, she's committed with little chance to recover. She needs her balance to react so realistically she should be establishing herself as a fielder first and target second.
The other thing to consider is the velocity of the throw. My fielders can throw a ball much faster/harder than my first base person can stretch outwards. I instruct my first base fielder to allow the ball to come to her. Once she gets the hang of being a fielder first it is much easier to teach her to reach or step towards the ball when recieving it. This isn't any different than when they learned how to catch back in their day when first learning. Think about it. We taught them to step towards their target when they throw and step towards the ball when receiving. Much more natural and fits instruction they learned.