Razor View if condition within foreach group to show either an a link

I have a foreach and several conditions within. Basically, I want to show an a link if PTWNoS is null and a span if PTWNoS is not null. The problem is I have a group and I don't know how to build the condition, similar with the one in the second foreach

@foreach (var group in Model.PTWContents.GroupBy(s => new { s.PTWMain.PTWId, s.PTWMain.PTWNo }).OrderByDescending(s => s.Key.PTWNo))
                    {
                        

                            @if (User.IsInRole("PTWIsoCert"))
                            {
                                

                                    @Html.DisplayFor(modelItem => group.Key.PTWNo)
                                
                            }
                            else if (User.IsInRole("PTWIsoCert"))
                            {
                                

                                    @Html.DisplayFor(modelItem => group.Key.PTWNo)
                                
                            }
                            else
                            {
                                

                                    @Html.DisplayFor(modelItem => group.Key.PTWNo)
                                
                            }
                            

                                @foreach (var item in group.OrderBy(s => s.StartDate))
                                {
                                    


                                        @if (item.PTWSubsequent != null && item.PTWSubsequent.PTWNoS != 0)
                                        {
                                            @if (User.IsInRole("PTWIsoCert"))
                                            {
                                                

                                                    @Html.DisplayFor(model => item.PTWMain.PTWNo) - @Html.DisplayFor(model => item.PTWSubsequent.PTWNoS)
                                                
                                            }
                                            else
                                            {
                                                

                                                    @Html.DisplayFor(modelItem => item.PTWMain.PTWNo) - @Html.DisplayFor(modelItem => item.PTWSubsequent.PTWNoS)
                                                
                                            }
                                        }
                                        else
                                        {
                                            

                                                No Subsequent
                                            
                                        }

                                        

                                            @Html.DisplayFor(model => item.PTWType)
                                        
                                        

                                            @Html.DisplayFor(model => item.WorkScope)
                                        
                                        

                                            @Html.DisplayFor(model => item.StartDate)
                                        
                                        

                                            @Html.DisplayFor(model => item.EndDate)
                                        
                                        

                                            @Html.DisplayFor(model => item.PTWStatus)
                                        
                                    
                                }
                            
                        
                    }