benedict XVII said:
Maybe you could assume that Kaiser Karl and the Habsburgs somehow managed to stay in power in the smaller Austria, that would also add a separator with Germany.
As for Italy, it did prevent a first attempt at Anschluss in 1936 (or 37? can't remember) by sending troops to the Brenner. Assume Mussolini does not get totally fascinated by Hitler during their subsequent meeting in Munich, and does the same in 38. You could have some interesting fighting going on in the Alps. Mussolini would then be seen as a worthy ally by Britain (Chruchill had a lot of admiration for him OTL) and even France.
The first attempt to annex Austria was in 1934, with the assassination of Chancellor Dollfuss. Mussolini deployed troops at the Brenner pass, and what was called the "Austrian civil war" fizzled down. There were some big changes 4 years later, even if Chancellor Schusnigg continued to oppose the anschluss up to the end: Italy's relations with UK and France were much colder, after the Abyssinian war and the sanctions imposed by the League of Nations (Germany and the USA did not follow the sanctions); neither France nor UK were ready or willing to take practical steps to oppose the annexation;
the Little Entente (the alliance of the MittelEuropean countries sponsored by France) was again not willing to be dragged into a conflict. Overall, it was a lost opportunity: before the Munich appeasement, this was the true opportunity to stop Hitler ambitions.
Who opposed the Anschluss in Austria? the Austrian Christian Social Party (a clerical party, with authoritarian tendencies and close to the Italian Fascism), who was the ruling party; the Austrian communist party, who declared their support for the government in the crisis of 1938 (at the same time, the Socialist party, which was bigger, tried to negotiate with the government, and weakened the Chancellor's position); the army was not nazified yet, and the Chief of staff, Gen. Jansa, had prepared a plan to resist the German thrust toward Vienna. The Chancellor had called a referendum on the Anschluss for the 13th of march 1938 (the invasion was on the 12th), even if the cut out age was at 24 years, to counter the sympathies toward nazism in the younger voters. The catholic church was again opposed to the Nazi anschluss, and this counted in a country like Austria.