From how much to spend on a gift to rules on using social media during the event, weddings can present some tricky situations.

To the rescue is etiquette expert Lizzie Post, co-author of "Emily Post's Etiquette, 18th Edition" and Emily Post's great-great-granddaughter. The sixth edition of "Emily Post's Wedding Etiquette," co-authored by Lizzie and her sister Anna Post, will be published in January.

Lizzie Post answers a few wedding etiquette questions to clear up the confusion.

Q: I'm invited to an engagement party and I'm unsure if I should give a gift.

A: To gift or not to gift depends on a few things, including local customs and how close you are to the bride and groom. If you're an immediate family member you would certainly want to give a gift. In many parts of the country, such as the South, engagement gift-giving is standard practice, but not so much in other areas. When in doubt, ask the host, and if you do bring a gift, it's a good idea to hold back and present it in private. You don't want others to feel awkward if they don't have gifts. If you are gifting, keep in mind you don't have to be over the top. A bottle of champagne to be opened on the first anniversary, an ornament for the holiday tree or a cookbook all make lovely engagement gifts.

Q: My father is alive, but we're not especially close. Can someone other than Dad walk me down the aisle?

A: Anyone can walk the bride down the aisle: a stepfather, a grandfather, your mother, a best friend, both mom and dad. Whatever makes the bride comfortable and makes sense to her is the right answer. That said, if your father will be in attendance at the wedding but not walking you down the aisle, consider giving him another special job to do, such as making a speech, participating in the first father-daughter dance or lighting the unity candle. Be sure to make your intentions clear before the wedding and be sensitive to his feelings, too.

Q: If I know someone can't attend the wedding, do I still need to send them an invite?

A: This is a tough one with no hard-and-fast rules. If you know someone can't attend, you shouldn't worry about sending them an invite, but you could also send the invite and include a note that says, "If your plans change we would love to have you attend." Remember: If you send an invitation you are obligating the recipient to send a gift. If you know someone won't be able to attend, most likely you're family or close friends, so you could add a note that reads, "I know you can't make it, but thought you might want to have this invitation as a keepsake."

Q: What are the rules about uploading wedding photos to social media during the wedding?

A: Since a bride and groom have hired a professional photographer to take photos, which won't be immediately available, posting wedding photos online is like stealing the bride and groom's thunder or scooping their news. It's also not positive to show others who aren't in attendance what they're missing. On the other hand, micromanaging your wedding and telling people they can't post photos is not acceptable, either. If you see unflattering photos online, you have every right to ask that they be taken down.

Q: I'm attending a destination wedding and it's costing me more than I expected. Am I still obligated to give a gift? Isn't my presence enough?

A: While your attendance at a wedding so far from home is a wonderful gift, you are still obligated to give a gift, which should be sent before the wedding or mailed within a month after the couple return from their honeymoon. Gifts don't have to be expensive to be meaningful. A simple, silver-plated picture frame engraved with their wedding date or any other small, heartfelt token will be appreciated.