I am a Stata user, so I don't know the particular code you need for SPSS. However, I do use time series analysis regularly, so I can address some aspects of your question. I am not sure what you mean by "flow chart" since that is not a term relative to TSA. I believe what you are asking is how add in a second time series? I am not sure if SPSS can run more than one series in a model, so you may have to run the two series separately and then compare the relevant parameter across models. For example, Stata will only accept one time series in ARIMA. It is possible to run two seperate models and then compare the parameter using a Wald estimate.

Better yet, I would recommend using a time-series regression, thus you can have more than a single series and compare the relevant parameter within the same model.

I am attaching a link to a paper I recently wrote on time series regression in a treatment effects context. Perhaps this may give you some ideas...

Article Applying a propensity-score based weighting model to interru...

thank you sir. By the term flow chart I mean to say the working procedure of doing ARIMA in SPSS. your paper helps me a lot. thanks

Thank you for the clarification. You may find this paper also helpful, since in it I speak specifically about ARIMA modelling

Article Evaluating Disease Management Program Effectiveness: An Intr...

thank you sir

You're welcome. Good luck!