From lower court to supreme court, all the judgments go in your favour for two reasons. The first reason is your husband's financial contribution is there in acquiring the property. The second reason is that your husband has been living in that property. The definition in Section 2(s) of the Act (in the last part) says "....... includes such a household which may belong to the joint family of which the respondent (here your husband) is a member, irrespective of whether the respondent or the aggrieved person has any right, title or interest in the shared household". So your husband's title is not mandatory, but his stay there in joint family is important factor to decide the case.
Regarding your FIL's impleadment, whatever may be the order of the Court (whether the court allow him or not) , that does not materially change the merits of the case and your position will not be disturbed. On second thoughts, my observation is that if FIL is joined as respondent and as you have already got the order for shared household, he would be bound by this order and any violation on his part would attract penal provision (imprisonment) of the Act.
Normally, in DV cases, the aggrieved party generally adds FIL, MIL, unmarried SIL along with husband as respondents, if she seeks the residential order. The reason behind this is that the order will be bound by all these people and no one can restrain the aggrieved wife and the children to enjoy the shared household. If she leaves any one of them, that particular person may physically obstruct the aggrieved wife to enter the residential premises. To avoid this situation, generally all the persons living in shared household will be added as respondents.