Page 7 of 11 says, "If you are unable to provide the original document, we may accept a copy certified by the body or authority which issued the original (for example, a copy of a savings book certified by the building society or bank), or by a notary. The reasons for not being able to provide the original document must be explained in a covering letter. We are unlikely to grant your application without the original document. Any documents which are not in English must be accompanied by a reliable English translation. Make sure passports or travel documents are signed".
You have to tell Home Office that you need to make a travel in those date (i.e from xx-xx-xxxx to xx-xx-xxxx). Please bear in mind that you are not the applicant, your dependant is the applicant(s) now so I dont know think there would be any problem if you get all of the pages of your passports(s)/BRP certified by the solicitor/notary
https://www.gov.uk/government/uploads/s ... _04-15.pdf
for your help.