RD>// Форма
RD><form asp-controller="..." asp-action="..." method="post"/>
RD>   <input asp-for="ParentProperty1">
RD>   <input asp-for="ParentProperty2">
RD>   <button name="button" value="parent">Save Parent</button>
RD>   @for (var i=0; i<Model.Children>length; i++)
RD>   {
RD>      <input type="text" asp-for="@Model.Children[i].Property1"/>
RD>      <button name="button" value="save-child-@Model.Children[i].Id">Save Child</button>
RD>      <button name="button" value="delete-child-@Model.Children[i].Id">Delete Child</button>
RD>   }
RD></form>

RD>// Контроллер
RD>public IActionResult Save(InputModel input, string button) {
RD>  if (button == "parent") {
RD>    // TODO: Update parent
RD>    return View(input.ToViewModel());
RD>  }
RD>  if (button.Contains("save-child-")) {
RD>    // TODO: Parse child id from button name, update child
RD>    return View(input.ToViewModel());
RD>  }
RD>  if (button.Contains("delete-child-")) {
RD>    // TODO: Parse child id from button name, delete child
RD>    return View(input.ToViewModel());
RD>  }
RD>  if (button == "new") {
RD>    var vm = input.ToViewModel();
RD>    vm.Children.Add(new Child() {});
RD>    return View(vm);
RD>  }
RD>}
RD>