tomodachi wa hanabi no shashin o kaigai ni iru kazoku e okutta.

My friend sent photos of the fireworks to family overseas.

Breakdown of tomodachi wa hanabi no shashin o kaigai ni iru kazoku e okutta.

• は: topic particle
• を: direct object particle
• 友とも達だち: friend
• の: possessive case particle

Questions & Answers about tomodachi wa hanabi no shashin o kaigai ni iru kazoku e okutta.

What role does の play in 花火の写真?

The particle の here is linking two nouns, functioning like the English “of.” 花火の写真 literally means “fireworks’ photo,” or more naturally “photos of fireworks.”

Why is は used with 友達は instead of が?

は marks the topic rather than the subject. By saying 友達は, you’re setting “my friend” as the topic of the sentence (i.e. “As for my friend…”). If you used が (友達が送った), the nuance would shift to introducing “the friend” as new information or emphasizing that it was specifically the friend who sent them.

Why do we use 家族へ送った instead of 家族に送った? Aren’t へ and に both used for “to”?

Both particles can indicate direction or recipient, but they have slightly different feels.

• 家族に送った is neutral: “sent to the family.”
• 家族へ送った has a more directional nuance, like “sent off toward the family.”
  In many contexts they’re interchangeable, but へ often feels a bit more “to that direction/recipient.”

What is 海外にいる家族 doing in this sentence? It seems to be three elements in a row.

This is a relative clause. 海外にいる (“who are overseas”) modifies 家族 (“family”) without any extra particle. So 海外にいる家族 means “(the) family who are overseas.” In English we’d say “my family overseas” or “the family that’s overseas.”