These are questions the royal bride-to-be Meghan Markle will have grappled with. And with the newest addition to the royal family Prince Louis only a couple of weeks' old, speculation is growing as to whether Prince William and Kate Middleton's new baby will make an appearance at the year's most eagerly anticipated wedding.
Seasoned royal watchers claim that with considerable interest in the new baby, William and Kate will not want to take the limelight away from Meghan and Harry on their big day and so will leave Prince Louis at home. However, it is expected that the couple's other two children Prince George and Princess Charlotte will be part of the ceremony as page boy and flower girl.
And while Meghan no doubt has a coterie of planners and advisors to help her with all things etiquette, the question of whether or not to make children and babies part of their big day is a question most couples have to decide upon.
You may want your own nieces and nephews at the wedding, but does this mean you have to invite all the children of all your friends, and if you don't ask them, will your guests be offended?
Wedding consultant Blaithin O'Reilly Murphy says it's a very personal decision and while some couples embrace having children at their wedding and want them to be involved in the ceremony, others have a strict no under-18s policy.
Blaithin says while there isn't a strict etiquette around the issue, the one thing that is very important to observe is if the children are not invited, guests shouldn't try to sneak them in and hope for the best.
She recalls being at one wedding where a bride simply "lost it" when she spotted children at the drinks reception. "It's a very personal thing. I would say if you're having more than seven children, it might be a good idea to have someone to take the kids off and watch a DVD until 9 or 10pm and then it's up to the parents to mind them. If it's only one or two children at the wedding, it's up to the parents to look after them," says Blaithin. She says it's clear that if a child's name is not on the wedding invitation, they are not invited. "If your kids are over 18 they're entitled to their own invitation, but if it's a younger teenager and their name is not listed, they're not invited."
Blaithin says some couples can opt to only have the children of their siblings and no other children at the wedding and people should reconcile themselves with this decision. She says the waters can be muddied if the couple begin to cherry pick other children outside of family.
"At the end of the day, it's entirely up to the couple to choose who they invite but in the interest of peace it is good practice to be clear about who is invited. Children bring great charm to a wedding but they can also bring chaos," she says.
Sandra Losty, a wedding solemniser with the Spiritualist Union of Ireland, says it can be a contentious issue and it is something she discusses with couples. "I'll get them thinking about things they maybe haven't thought about. I just flag with them that it is something they need to put some thought into," she says.
Sandra says while couples may want to have the children of friends at their special day, they don't want anything to take away from the ceremony and can be upset if a friend doesn't take a crying child out while the ceremony is taking place.
And she says while it may be difficult, it is better to have the conversation with a friend about what they'll do if their baby gets upset during the ceremony.
"It's one of those things people will avoid having the conversation about, but it helps to have the conversation," says Sandra.
Mum-of-two Claire Flannery from Dublin says she took her eldest son Seamus to the wedding of her best friend when he was only three weeks old but only after she'd discussed it with the bride first.
"If it had been someone else's wedding, I wouldn't have gone but I really wanted to be at my friend's wedding. I was pregnant when she was planning her wedding and I asked her if it would be okay to bring the baby. I think you do need to ask rather than just assume.
"It was my first baby, so I was trying to figure out what to pack and the other challenge was I was at the start of my breastfeeding journey and wasn't really comfortable feeding in public. I gave him a bottle on the day and that messed up feeding a bit and it took me a day to get back on track," she says.
"The wedding ceremony was brilliant and it was really nice to be there. I had Seamus in a sling all day and I left before the music got too loud. I could see how he was doing because he was in the sling on me all day. Overall, having a baby at a wedding was a fine experience.
"In general, for me it's mum and baby at the wedding or nobody. When you have a small baby and you're going to a wedding they should be able to go with you. My advice would be to talk to the bride and groom in advance," says Claire.
Niamh Hogan from Wexford got married to her partner Paul Hickey last summer and while they invited the children of family members, no other children were invited.
"We had a small venue and we were keeping costs down. What we did was invite family and all their kids but to friends we said no kids except for friends with babies. To be honest, most parents don't want to bring kids," says Niamh, who is mum to Bella (13).
However, she says it's different for mums of new babies and couples couldn't expect a new mum to leave her baby at home.
"I think that it's fine to have rules but there has to be give with a baby. I think the bride and groom should speak to the mum with a small baby to see what way they can help. It has to come from the bride and groom.
"You can imagine how difficult it would be for a guest to pick up the phone. What happens is the mum will decide not to go and then it's a case of 'why is she not going?' and it's awkward."