Star 7 in period 8, tend to trigger dissolute behaviour, misfortune caused by arguments, and venereal disease, depends on person conduct of relationship affairs. It will also affect the pregnant woman in the house and cause miscarriage. Depending on what stars it pairs up with, there also chance of suffering from cholera and dysentery disease.
Star 7 also represent metal. Linking to accidents and fighting. Areas of misfortune caused by “verbal” problems which may result in litigations and lawsuits, and robbery. Pair with wood stars may mean surgery and traffic accidents.
It would worsen once period 9 finishes.
Since on this topic, for example West facing apartment in period 7 ( 卯山辛向，七运 ). It has an auspicious combination of Sitting and Facing star 7 （到山到向）. Once it moves into period 8 and it the west sector is still frequently use this sector or this room. The effects of it may be quite detrimental, with potential legal suits, defamation, family and office politics such as gossips that take away energy and risk of accident. The same apartment, same facing same period, if the residents make use northwest and southeast, they may actually still receiving good energy. Although the apartment is not in period.
Firstly, in my opinion, the Flying Star school if pretty much divided. If you go search the chinese sites on the internet, you will see many different school of Flying Star Feng Shui (i.e. 沈氏飞星； 骆氏飞星； 温氏飞星； 无常派 ) . If a discipline is very much divided, it is very inconsistent and takes effort to consolidate the theory and application. This makes it very challenging for the later generation of practitioners to learn and apply. I believe (in the olden days) Flying Star was adopted and fine-tune to cater for each of the domestic location and needs. So now, in modern days now, we see a lot of division in just this one discipline.
Moreover, if you related flying star to QMDJ you also see some similarities. So, in all likelihood, Xuan Kong Flying Star ( XKFS ) is gear towards divination or assessment (to gain client’s trust and reverence ) rather than Feng Shui solution.
Next, the period which the property is in; is also already a quite debatable aspect, whether to use upper yuan / lower yuan ( meaning 二元八运 ) or 3 yuan way （三元九运）. Even in upper yuan/ lower yuan method there is equal division of years and period method or the other way which follows gua which is uneven distribution of years between period.
The date the owners move in or open door or to use the date the building is build is also debatable. This becomes critical when the period cross from 7 to 8 or the coming 8 to 9 (i.e. House build in period 7, owner move in at period 8). When it become a rental property or change hands, which period become debatable since period 9 is coming, most practitioner will face this problem.
Also, in the context of apartment. Where to take the compass reading will also raise question of accuracy of application. Whether to use Door, Balcony Window, Building Door or Building Facing? The building facing direction most of the time will be different from the units facing.
Historical, it was stated in Chinese Metaphysics book that the Emperor used the day of Winter Solstice as the first day of the year in the Rat month, this is very iChing (i.e. 冬至是“一阳生”). The first Stem-Branch is Wood Rat (甲子). Chinese trace back the Emperor should found the nation in 2697 B.C. How do we know that the person recording the history accurately without bias recorded those information. They work for the Emperor don’t they ?
Since Xuan Kong Flying Stars ( 玄空飞星 ), relates to stars and 5 elements ( 明玄空，只在五行中，知此法，不须寻纳甲 ). In my opinion the commencement of flying stars probably started during the great conjunction of the 5 planets instead of actual stars (i.e. Mars, Venus, Mercury, Saturn and Jupiter) which represent the 5 element in Chinese Metaphysics (水星, 木星, 火星, 土星, 金星). And since XKFS is related to the planetary conjunction (instead of actual stars), the change in each period which is 20 years shares vital similarities with the conjunction of Saturn and Jupiter which is approx 19+ years. Therefore, the historical dates which tracks each period and cycle is inherently incorrect from the start, due to naked eye observation and weakness in space technology. And could have gradually deviate because of the approx. 1 year gap between 20 years vs 19 years. I think I deviate from topic, I’ll stop here, the details and dates + article URL are on my website.
As for star 7. first question is are you using that star or not? If not using that room or that star but in the natal FengShui chart it’s ok. It shouldn’t raise much concern. If yes, concern is whether the annual stars trigger and activate it or not. Or you happen to be in the annual stars position. If you happen to be using that sector and have the space to adjust, do the adjustment and you be fine. If using and can’t adjust room, you realign internally to use your auspicious direction in 8 mansion position. Remember to activate all 3 of it internally (生气、延年、天医三吉方). Alternatively, the use of Salt water placement, salt lamps or Selenite, which is not an expensive crystal. Its regarded as a protective stone, shields a person or space from outside influences or negative Qi. In the west, Selenite is associate with good luck and protection.
As for a period 7 property, it is absolutely fine to have a period 7 property and still remain prosperous. It all depends on which stars or sectors you are using.
Also the landform in terms of the basic 零正催照 (I think they call it spirit in this forum) and the application of Qi is more vital than XKFS. A more robust application on the landform and water mouth should be using SanHe and LMBDJ. HTP Feng Shui is also a holistic approach. For Qi the more developed discipline is SYNQ and XKDG.