Create a Schema from an existing one? - sql-server

Question

I have two databases:
database A with missing indexes,constraints,foreign keys etc ...
database B with all the missing features
I have loaded the schemas of the two databases in my C# code and after comparing them I added the missing features to the first schema.
Now I want to update that schema back to SQL Server. How to do that? Could I create a schema from an existing schema?
This is what I have tried:
public static void Compare(ref DbMetaData dbSchema , ref DbMetaData dbSchema2)
{
foreach (var schemaGroup in dbSchema.SchemasDic.Values )
{
DbUserSchemaInfo schemaGroup2=dbSchema2.SchemasDic.Values.First(sc => sc.SchemaName == schemaGroup.SchemaName);
foreach (var x in schemaGroup.TablesDic)
{
var y = schemaGroup2.TablesDic.First(sc => sc.Value.TableName == x.Value.TableName);
// GET the difference in columns
var colDiff = x.Value.Columns.Except(y.Value.Columns);
// GET the difference in indexes
var indexDiff = x.Value.Indexes.Except(y.Value.Indexes);
// GET the difference in constraints
var constraintDiff = x.Value.DfConstraints.Except(y.Value.DfConstraints);
// GET the difference in Fk
var foreignKeysDiff = x.Value.ForeignKeys.Except(y.Value.ForeignKeys);
//check if a primary key exists
var primaryKeysDiff = y.Value.PrimaryKey == null ? x.Value.PrimaryKey : null;
// GET the difference in triggers
var triggersDiff = x.Value.Triggers.Except(y.Value.Triggers);
//merge the difference
if (indexDiff.Count() != 0)
{
foreach (var index in indexDiff)
{
y.Value.AddTableIndex(index.Value);
}
}
if (constraintDiff.Count() != 0)
{
foreach (var constraint in constraintDiff)
{
y.Value.AddDefaultConstraint(constraint.Value);
}
}
if (foreignKeysDiff.Count() != 0)
{
foreach (var foreignKey in foreignKeysDiff)
{
y.Value.AddFk(foreignKey.Value);
}
}
if (triggersDiff.Count() != 0)
{
foreach (var trigger in triggersDiff)
{
y.Value.AddTableTrigger(trigger.Value);
}
}
}
}
//Update DbSchema in sqlserver
}