The experience sampling method (ESM) is widely used for collecting in situ experiences in various domains. One known limitation, however, is its reliance on participants being receptive to ESM questionnaires at the sampled moments. At moments when participants cannot notice or respond to an ESM questionnaire, researchers cannot obtain a response. In this research, we explored the feasibility of inviting peers to provide information about participants in an ESM study. Results from a two-week experiment with a total of 27 participants and 82 peers showed that including peers' ESM responses increased ESM data quantity. Furthermore, the agreement between the peers' and the participants' responses could be maintained by asking peers' confidence. Even considering only data with high confidence could increase data quantity. Moreover, inviting peers had a positive impact on the participant's compliance to respond. These results suggest that using peer-ESM to obtain more in-situ data about participants is promising.