Playing with and practicing with older girls are two different things.
When DD 3 was a first year 12U, she was invited to practice for a while with a 16U team her older sister had previously played on. The older sister of one of DD 3's TB teammates was on the team as well, and was also an apprentice AC for DD 3's 12U team.
One time both teams were in the same tournament. The 12U girls were encouraged to go watch the older girls play. The other 12U girls were extremely impressed with DD 3. Whenever a girl from the 16U team was at bat, or else made a great play, DD 3 knew her name and knew the girl. It made DD 3 seem much older and wiser to the young girls. OTOH, the 16U players were clearly better than DD 3. There was no question she wasn't good enough to play for them, although when she was a 2nd year 10U she once guest played for a 14U team that otherwise would only have 8 players.
When DD 3 was a first year 12U, she was invited to practice for a while with a 16U team her older sister had previously played on. The older sister of one of DD 3's TB teammates was on the team as well, and was also an apprentice AC for DD 3's 12U team.
One time both teams were in the same tournament. The 12U girls were encouraged to go watch the older girls play. The other 12U girls were extremely impressed with DD 3. Whenever a girl from the 16U team was at bat, or else made a great play, DD 3 knew her name and knew the girl. It made DD 3 seem much older and wiser to the young girls. OTOH, the 16U players were clearly better than DD 3. There was no question she wasn't good enough to play for them, although when she was a 2nd year 10U she once guest played for a 14U team that otherwise would only have 8 players.