Edit: Sorry about this being so long. I'm trying to summarize two decades of coaching kids.
I feel for you. It's a tough situation. Be proud of your daughter and she should also be proud. All kids should know what it feels like to excel. Don't worry about game one, but use this strength to develop the rest of your team. Just as your daughter is learning to play ball, you are learning to coach children.
I coached ball for amost two decades and almost to a man, coaches that I knew over those decades gained, over time a better perspective about what we were doing. In the end you realize it is a kids game and as a coach you have a responsibility to all the kids involved.
I had bag of tricks for keeping a game close. My favourite technique in little league was what I called the clock killer. It works for home games if your league has a game time limit. Our league had a rule that if time runs out before an inning is complete, you revert to the previous inning's score. You have to trust the ump, but be sure to confirm start and end times at the pregamp coin toss. Based on game pace and only enough time for another inning, put a developing pitcher on the mound. I always had mound hopefuls who were the go to guys for this. While your at it, try other kids out in the infield as you see fit. Explain clearly to the pitcher that their job is to throw strikes and let the defense get the outs. When you sub the clock killer in, discretely double check game end time with the ump. But don't let the other teams nose get rubbed. Let the other team swing away and make a come back. Watch your pitcher's facial expression (don't let her get upset or worse yet, cry). Go to the mound as the lead slips away and explain the time rule and that the game outcome is safe. If the new pitcher can run the clock out, you do not get your home at bat and score reverts to the previous inning. The end result can be good all around. Your team got some new experience and development. The other coach gets to praise his kids for the comeback.
Any combination of the above can be used to control a game if you have thought it out in advance.
By the time my team core was 12 they were an out getting, base running machine. It was fun to just watch. We had no stars, but had few holes.
The intent it to make it exciting for all kids, even the right fielder on the weak team. You gotta remember these are kids and he also has the same MLB dream as the short stop. If a team gets blown out consistently, some kids won't be back. Your league shrinks every year.
Once your kids develop, this will get easier to pull off, even without a time limit. Short shift the pitchers. Ie; starter, equalizer, closer. Water down the defense. Take the steal off. Swing at the plate, no waiting for the walk. Once playoffs come around, this adds up to additional depth in your roster.
I explained my no blowout philosophy to my team as required. It's for the good of the league. Win with class, lose with class.
We did well at the nationals one year, but my proudest moments of coaching include;
-Turning a surprise 14 point lead in high school into a 3 point win. (Adam's grandpa got to see him pitch that day.)
-Having close games against the weakest teams in house league.
-Coaching against one of my pitchers from the nationals and watching him throw BP to my inexperienced squad. Giving up his (and getting our) first home run in that game and smiling as he let us hang in a few runs back before he winked at me and then struck us out to end an exciting game.
Remember, you're building characters, not dynasties. Good luck and have fun with the kids.