The bilingual preschooler Juli (age 3;7) began to use an indefinite pronoun something/someone in American Sign Language a little while ago. Since then, she used it sometimes. Note that the ASL signed "something" and "someone" are about the same production.
Prior to using the "something/someone" pronoun in ASL, Juli had used #all and many pretty naturally for the past months that I didn't recognize as the firsts. However, now "something/someone" is something that stands out among the indefinite pronouns.
For some examples, one day Juli and I were sitting under a table in a toy store. A garbage under the table fell down. Juli looked around and signed something fell-down. She looked under and I followed, ah. We both signed garbage.
Another day, she was scared in her dram and woke up. She signed something huge fell-down.
At age 3;7, Juli was seen sometimes using another/other and some. For example, I asked her about her classmate, you see (signed name) in your class?. She replied, ix-he in another class.
Another time, Juli noted some juices bad, some juices good, healthy.
Juli also was observed, using a plural pronoun you-two. At age 3;9 (October), Juli told me, ix-me like father and you, both-of-you (using the "2" handshape for the plural).
Some of the following examples that Juli had uttered in American Sign Language during this month in August: university, and some more.
One day in late August, I received a great news. I told Juli, ix-me got job!. She looked at me, university said yes. I nodded. She knew that if I could get a contract teaching at the university, I'd be able to support her participation in gymnastics. She signed now ix go-to gymnastics.
Another day, Juli came to me out of blue sky, hey, my heart hurt. I asked, why? She continued, man in ix-ref(chest)++. Ate, swallow-down ix(stomach). I asked, who man? She thought for a moment, ix-me not dunno.
At age 3;9, Juli was using a quantifier VERY, ix-me very sorry. She came to me when my Portugese souvenir was broken.