Can this party play LMOP without too much trouble?

I started recently to DM Lost Mine of Phandelver for a party of friends and I’m planning to start to DM it for a party which will be my three sisters.

We started creating character sheets, and I wonder if they can play the basic adventure without me needing to lower the difficulty.

Their party would be:

  • Barbarian goliath
  • Ranger tiefling
  • Sorcerer elf

The barbarian is going full about doing lots of damages, more likely to go for berserker, the ranger isn’t for now sure if she wants to focus on ranged, melee or both, and finally the sorcerer chose draconic bloodline and is more likely to also go for a full damage character with few self protection spells.
What worries me is that they don’t have a very strong front line, basically only the barbarian as if the ranger goes melee it’s going to be more sneaky, and they don’t have any source of healing for now.

The group of friends I DM for being my only experience in D&D, I use it as a reference. This group is a party of 5 constituted of:

  • Rogue gnome
  • Paladin human
  • Magician elf
  • Warlock halfling
  • Monk human

Even for the first encounter, the rogue and the warlock fell unconscious multiple times, so the paladin basically was just running to heal them using Lay on Hands. This time I rolled several times max damage and the magician wasn’t here at that moment, but they had a hard time facing these enemies.

To add to these descriptions, my friends already played some other RPG systems, but my sisters will be very new RPG players.
As per my nearly non-existent experience in D&D, I can’t precisely tell if I have to balance the basic scenario to let my sisters enjoy the universe and have fun as much as I would like.

Do I have to adjudicate the basic scenario to lower the difficulty to a “normal” one?

By normal difficulty, I mean that one or two characters may fall unconscious during planned encounters and one or two may even die against a boss if players roll badly, if the boss rolls great or if they just go straight and don’t try to use their character’s potential.

Answers have to be backed up by experience as a player or DM for playing/running pre-published adventures for few players or “unbalanced” parties, bonus point to answers addressing particularly LMOP.