Use a separate folder and identity summary for each person, with a shared index of relationship records and unresolved discrepancies.
Prepare for consistent information
Compare names, dates of birth and relationships across existing records before counsel prepares the application. Mark missing records instead of guessing their contents. Obtain current agency instructions for required documents and translations; this organisational suggestion is not a definitive list of what every family must file.
Organize the family's records so that the same facts appear consistently everywhere, since inconsistency across documents is the most common practical obstacle a household encounters. For each person, hold the civil documents establishing birth and, where relevant, marriage, divorce or adoption, together with the passport or travel document and any immigration record. Where a document is issued in another language, obtain a certified translation and keep the original alongside it.
Reconcile names actively rather than hoping the variation passes: transliteration differences, a name changed on marriage, a middle name recorded in one place and omitted in another, and dates written in different conventions all need a supporting record that explains the difference. Note which documents have expiry dates and when, since a process running over a long period will outlast some of them. Where a document must be obtained from another country, start that request before the rest of the file is assembled, since foreign civil registries respond on their own schedule and no other preparation compensates for a late start.