fill in

verb

To fill; to replace material that is absent or has been removed.
“After you're done laying the pipe, fill in the trench.”
“The decking of the bridge consisted of steel troughing over an average clear span of 26 ft., the troughing being filled in with concrete to form the road surface.”
To inform somebody, especially to supply someone missing or missed information.
“If you know anything about this, maybe you can fill me in.”
To substitute for somebody or something.
“He can't go on vacation very often because there is nobody to fill in for him.”
To complete a form or questionnaire with requested information.
“I've got a form that is to be filled in in ink.”
“The findings emerged from questionnaires filled in by 2,211 staff in 145 wards of 55 hospitals in England and Wales and 105 observations of care of dementia patients. Two-thirds of staff said they had not had enough training to provide proper care, 50% said they had not been trained how to communicate properly with such patients and 54% had not been told how to handle challenging or aggressive behaviour.”
To beat up; to physically assault.
“Talk to me like that again and I'll fill you in!”
“It's just a rumour that was spread around town Somebody said that someone got filled in For saying that people get killed in The result of this shipbuilding”